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WASHINGTON  OBSERVATIONS  FOR  1869.— APPENDIX  I. 


REPORTS    ON    OBSERVATIONS 


TOTAL    SOLAR   ECLIPSE 


DECEMBER    22,    1870. 


CONDUCTED  UNDER  THE  DIRECTION  OF 
REAR-ADMIRAL    B.    F.    SANDS,    U.    S.    N., 

SUPERINTENDENT  OF    THE   U.    S.    NAVAL   OBSERVATORY,    WASHINGTON,    D.    C. 


WASHINGTON: 

GOVERNMENT   PRINTING  OFFICE. 
1871. 


Ui 


TABLE    OF    CONTENTS. 


Page. 

Report  of  Rear-Admiral  B.  F.  SANDS,  U.  S.  N.   .         .         .                   .         . 3 

Report  of  Professor  SIMON  NEWCOMB,  U.  S.  N.,  on  Observations  of  the  Eclipse,  &c.,  made  at  Gibraltar: 

Subjects  of  observation      ................;  7 

Position  of  station  selected g 

Description  of  instruments         ................  10 

Description  of  corona,  as  seen  ................  n 

Results  of  observations  of  contact       ...............  12 

AIIDKNDUM  A.  Observed  chronometer  times  of  contact,  and  distance  of  cusps  near  the  times  of  contact         .          .  13 

B.  Transits  of  the  cusps  over  the  wires  of  the  comet-seeker       .          .          .          .          .          .          .          .  14 

C.  Observations  for  instrumental  errors  of  telescope          .........  16 

D.  Observations  for  latitude     .........                    ....  17 

E.  Sextant  observations  for  correction  of  chronometer       .........  18 

F.  Observations  for  index  correction  of  sextant         ..........  ig 

G.  Transit  observations  for  correction  of  chronometer        .........  20 

H.  Determination  of  instrumental  constants  of  transit         .........  22 

I.  Exchange  of  signals  with  Malta  through  the  Falmottth,  Gibraltar  and  Malta  cable           ...  23 

Report  of  Professor  ASAPH  HALL,  U.  S.  N.,  on  Observations  of  the  Eclipse,  &c.,  made  at  Syracuse,  Sicily : 

Introductory 27 

Observed  times  of  contact           ................  27 

Comparison  of  observed  with  computed  times    ..............  28 

Description  of  the  eclipse 2g 

Sextant  observations           .................  30 

Results  for  latitude  and  time      ................  3g 

Difference  of  longitude  between  Malta  and  Syracuse            ...........  40 

Difference  of  longitude  between  Malta  and  Gibraltar           .                    42 

Report  of  Professor  WILLIAM  HARKNKSS,  U.  S.  N.,  on  Observations  of  the  Eclipse,  &c.,  made  at  Syracuse,  Sicily : 

I.  Introductory    ............                    .....  45 

II.  Site  of  observing-station            .          .          .   •                ...          .          .          .          .          .          .          .                    .  47 

III.  Description  of  instruments       ...............  48 

Magnifying  power  of  spectroscopes 4g 

IV.  Probable  error  of  observations  made  with  a  sextant            ..........  51 

V.  General  remarks  on  the  observations  for  time  and  latitude          .........  57 

VI.  Observations  for  time       ................  58 

VII.  Observations  for  latitude           ................  60 

VIII.  Triangulation  at  Syracuse: 

Measurement  of  base-line     ...............  61 

Adjustment  of  horizontal  angles  ..............  64 

Determination  of  azimuth     ........                    .......  67 

Results  of  triangulation        ...............  6g 

IX.  Telegraphic  determination  of  differences  of  longitude  : 

General  formulae           ................  70 

Latitude  of  Malta          ................  70 

Chronometer  corrections  at  Malta          .............  71 

Arrangement  of  telegraphic  apparatus            ............  71 

Difference  of  longitude  between  Syracuse  and  Malta      ..........  72 

Observing-stations  at  Gibraltar x  74 

Latitude  of  Gibraltar • 75 

Chronometer  corrections  at  Gibraltar    ..............  76 

Difference  of  longitude  between  Malta  and  Gibraltar      .          .                    76 


IV  TABLE  OF  CONTENTS. 

Paffe 
Report  of  Professor  WILLIAM  HARKNESS,  U.  S.  N.,  continued  : 

X.  Geographical  positions  determined  by  the  U.  S.  Naval  Observatory  parties         .  ->S 

XI.  Magnetic  declination  at  Syracuse      . 79 

XII.  Observations  on  the  day  of  the  eclipse  : 

Acknowledgments  •....".............  79 

Observations  of  the  eclipse  ..........                    ...  70 

Table  of  observed  times  of  contact       ............  82 

Origin  of  the  bright  line  seen  along  the  projection  of  the  moon's  limb  upon  the  solar  disk  in  photographs 

of  eclipses         ................  82 

Is  the  light  of  the  corona  polarized  prior  to  entering  the  earth's  atmosphere?           ...  82 

Spectrum  of  the  corona         ..........  82 

Physical  constitution  of  the  corona        ............  83 

ADDENDUM  A.  Record  of  observations  for  time  at  Syracuse         ........  88 

B.  Record  of  observations  for  latitude  at  Syracuse  ..........  107 

C.  List  of  articles  forming  part  of  the  equipment  of  the  expedition  to  Syracuse         .         .         .         .116 

D.  Letter  of  Captain  Tupman,  R.  M.  A.  .         .         .         .         .         .         .         .         .         .         .         .117 

Report  of  Professor  J.  R.  EASTMAN,  U.  S.  N.,  on  Observations  of  the  Eclipse,  &c.,  made  at  Syracuse,  Sicily- 
List  of  instruments  ................  123 

Description  of  instruments         ...............  123 

Position  of  observing-station     ................  123 

Meteorological  observations  before  December  22d      ............  124 

Plan  of  observations.         .................  125 

Observations  on  the  22d  December: 

Weather  before  the  total  phase          ..............  126 

Observations  of  first  and  second  contacts          ..........  126 

Observations  with  the  polariscope    .  '       .         .         .         .         .         .         .         .         .         .         .         .         .126 

Structure  of  corona          ...............  127 

Structure  of  the  principal  prominence      .............  127 

Observations  of  third  and  fourth  contacts          ............  127 

Meteorological  observations    .............  I28 

Comparison  of  chronometers  .........  528 

Curves  representing  the  observations  with  the  dry  and  the  wet-bulb  thermometers      .         .         .         .         .         .129 

Curves  representing  the  observations  with  the  solar  thermometer 130 

Comparison  of  observed  with  computed  times  of  contact  .......                   ...  131 

ADDENDUM  A.  Meteors  observed  at  Syracuse     .......  132 


LIST    OF    ILLUSTRATIONS. 


Page. 

Arrangement  of  wires  in  eye-piece  of  comet-seeker    ......                    .....  10 

Diagram  of  spots  on  the  sun  at  noon  December  22,  1870     ....                                        ....  28 

Relative  positions  of  observing-stations  at  Syracuse    ............  48 

Path  of  a  ray  of  light  through  a  spectroscope      .............  49 

Patli  of  a  ray  of  light  through  Browning's  direct-vision  spectroscope            ........  50 

Plan  of  base-line  at  Syracuse     ...;.....                    ......  61 

Plan  of  triangulation  at  Syracuse       ...............  63 

Arrangement  of  telegraphic  apparatus  for  use  in  determining  differences  of  longitude          .....  71 

Diagram  of  the  corona,  December  22,  1870         .............  117 

Diagram  of  part  of  the  corona,  showing  the  portion  examined  spectroscopically  at  a  certain  time  .  .  .  118 
Mean  curves  of  the  dry  and  wet-bulb  thermometers  for  six  days,  together  with  the  curve  from  the  observations  on 

December  22,  1870       .................  129 

Mean  curve  of  the  solar  thermometer  for  six  days,  together  with  the  curve,  from  the  observations  on  December 

22,1870       .          .          .          .          .' 130 


PLATES. 


PLATE  I.  Colored  drawing  of  the  total  solar  eclipse  of.  December  22,  1870,  as  seen  at  Syracuse,  with  a  ij--inch  telescope, 

by  Captain  G.  L.  TUPMAN,  R.  M.  A. 

II.  Colored  sketch  of  the  corona  and  protuberances  on  the  western  limb  of  the  sun,  near  the  end  of  the  total 
phase  of  the  eclipse  of  December  22,  1870,  by  Professor  J.  R.  EASTMAN,  U.  S.  N. 


LIST    OF    ERRATA. 


NOTE.— The  sign  —  placed  before  the  number  of  a  line  indicates  that  it  is  to  be  counted  from  the  bottom  of  the  page. 
Page    10,  line  18.  For  adjustmenr  read  adjustment. 
Page    48,  line  —  13.  For  8.87  inches  focus  read  8.78  inches  focus. 

Page    55,  line  5.  For  p     =m.-      \  read  pm=m  .  — ^i 

m+e  m+o 

Page    84,  line  6.  For  that  of  the  moon  to  be  3963  miles  read  that  of  the  moon  to  be  2153  miles. 

Page  119,  line  —  I.  For  atitude  read  latitude. 

Page  131,  line  —  18.  For  Mr.  Rosenbusch  read  Mr.  Edward  Rosenbusch. 


REPORT 


REAR-ADMIRAL    B.    F.    SANDS,  U.  S.   N. 


1— B 


REPORT   OF   REAR-ADMIRAL   B.    F.    SANDS,   U.  S.  N 


UNITED  STATES  NAVAL  OBSERVATORY, 

}}~asliin«ton,  July  15,  1871. 

SIR  :  The  officers  of  the  Observatory,  detailed  by  the  Navy  Department  for  observations  of  the  late 
eclipse  of  the  sun  of  the  22d  December,  1870,  having  returned  from  that  duty,  I  have  the  honor  to  forward 
herewith  their  reports. 

After  the  successful  results  of  the  observations  of  the  eclipse  of  August  7,  1869,  by  the  officers  of 
this  Observatory,  it  was  desirable  that  their  experience  should  be  taken  advantage  of  for  the  further  eluci- 
dation of  the  subjects  involved  in  such  phenomena;  and  the  eclipse  to  occur  in  Europe  on  the  22d  Decem- 
ber, 1870,  was  discussed  with  a  view  to  their  taking  part  in  the  observations  on  that  occasion,  as  one  of 
the  legitimate  and  appropriate  duties  of  the  Naval  Observatory. 

The  Navy  Department  was  addressed  by  me  upon  the  subject,  which  resulted  in  the  detail  for  that 
duty  of  Professors  Simon  Newcomb,  Asaph  Hall,  William  Harkness,  and  J.  R.  Eastman,  of  the  United  States 
Navy,  attached  to  this  Observatory,  all  of  whom  had  contributed  largely  to  science  by  their  reports  of  the 
August  eclipse. 

It  was,  at  first,  intended  to  have  the  parties  accompanied  by  a  skilled  photographer  and  other  observers 
not  attached  to  the  Observatory ;  but  having  no  special  appropriation  for  the  purpose,  and  our  contingent 
fund  being  too  limited  to  meet  the  expense  that  would  be  incurred,  we  had  to  restrict  ourselves  to  the 
officers  of  this  institution  already  experienced  in  such  observations. 

The  last  three  of  the  officers  mentioned  above  were  directed  to  proceed  to  Sicily,  to  occupy  some  con- 
venient points  near  Syracuse,  each  in  his  distinct  and  separate  duties,  with  independent  instructions  for 
each — Professor  Hall  for  observations  upon  the  corona,  Professor  Harkness  for  spectral  analysis,  and  Pro- 
fessor Eastman  with  polarizing  apparatus  and  meteorological  instruments ;  with  directions  to  avail  them- 
selves of  any  assistance  they  might  be  able  to  obtain  in  the  localities  selected. 

Professor  Newcomb,  having  been  previously  detailed  for  other  special  duties  in  Europe,  .was  instructed 
also  to  occupy  some  point  near  Gibraltar  for  general  observation  of  the  eclipse  and  physical  constitution  of 
the  corona,  and  other  observations  to  determine  the  path  of  the  center  of  the  shadow  over  the  earth,  with 
the  object  of  obtaining  data  for  the  correction  of  the  lunar  tables,  by  comparing  these  results  with  those 
previously  calculated  from  them. 

While  in  England,  en  route  for  his  station,  Professor  Newcomb,  through  the  courtesy  of  the  Astron- 
omer Royal,  Mr.  Airy,  and  of  Sir  James  Anderson,  the  president  of  the  Anglo-Mediterranean  Telegraph  Com- 
pany, made  very  elaborate  arrangements  to  correct  the  stations  of  our  observers  by  cable  for  difference  of 
time  with  the  Greenwich  Observatory.  This  was  accomplished  between  Sicily  and  Malta  and  Gibraltar, 
and  failed  with  Greenwich  only  in  consequence  of  a  break  in  the  cable  between  that  place  and  Lisbon, 
which  could  not  be  repaired  during  Professor  Newcomb's  sojourn  at  Gibraltar. 

By  special  invitation,  Professor  Newcomb  accompanied  the  English  party  to  Gibraltar  on  board  H.  B. 
M.  Steamer  Urgent,  arriving  in  time  to  make  the  necessary  preparations  for  telegraphic  difference  of  time 
with  Greenwich,  Gibraltar,  and  Malta. 

Professors  Hall,  Harkness,  and  Eastman  arrived  at  Syracuse  with  their  instruments  in  ample  time  to 
make  every  preparation,  and  selected  their  several  positions  near  that  city.  Mr.  Hall  and  Mr.  Harkness,  in 
the  mean  time,  at  Malta  and  Syracuse  respectively,  in  connection  with  Mr.  Newcomb  at  Gibraltar,  deter- 
mined by  telegraphic  cable  the  difference  of  time  between  those  places.  Cloudy  weather  with  high  winds 
made  the  Sicily  observations  less  successful  than  we  had  hoped,  but  they  tend  to  corroborate  those  of  our 
parties  in  America  on  the  7th  August,  1869,  and  form  interesting  addenda  to  those  of  that  year  on  this 
continent. 

In  accordance  with  the  course  I  had  adopted  in  the  administration  of  the  duties  of  Superintendent,  to 
give  to  each  of  the  officers  the  full  credit  of  his  work,  and  that  they  may  share  the  responsibility  attendant 
upon  their  observations,  I  have  the  pleasure  to  forward  to  the  Department  their  very  interesting  reports 


4  OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 

entire,  and  over  their  several  signatures.  Constituting  as  they  do  very  valuable  contributions  to  the  science 
of  astronomy,  evincing  great  ability  and  personal  interest  in  the  subject,  most  creditable  to  the  observers 
and  highly  honorable  to  the  institution  of  which  they  are  prominent  members,  it  would  be  unjust  to  the 
officers,  and  detract  from  the  merits  of  the  reports,  to  abridge  or  condense  them. 

The  letter  of  Captain  Tupman,  R.  M.  A.,  who  volunteered  to  assist  Professor  Harkness,  containing 
his  notes  and  other  remarks,  is  also  given  entire  at  the  end  of  Professor  Harkness's  report.  The  reports 
have  been  delayed  to  this  date  by  the  severe  illness  of  Mr.  Harkness  in  Europe,  and  the  detention  of  Mr. 
Newcbmb  by  other  duties  on  which  he  was  engaged,  and  which  were  protracted  by  the  war  in  Europe. 

It  is  most  gratifying  to  record  here  the  very  great  courtesy  and  kindness  extended  to  our  officers  by  the 
savants  of  Great  Britain  and  the  continent — setting  aside  national  jealousies  and  forming  one  great 
brotherhood  of  science.  To  each  of  those  learned  and  distinguished  gentlemen  I  have  had  the  pleasure  to 
address  a  letter  expressing  my  appreciation  of  the  attentions  thus  shown.  They  are  mentioned  by  name  in 
the  several  reports  of  our  officers. 

Through  the  courtesy  of  the  Secretary  of  State,  Hon.  Hamilton  Fish,  we  secured  the  ready  acqui- 
escence of  the  foreign  legations  of  England  and  Italy  for  the  passage  of  the  instruments  used  through  the 
several  custom-houses. 

I  have  the  honor  to  be,  very  respectfully,  your  obedient  servant, 

B.  F.  SANDS, 
Rear- Admiral,  Superintendent. 

Hon.  G.  M.  ROBESON, 

Secretary  of-  the  Navy,  Washington  City. 


REPORT 


OF 


PROFESSOR  SIMON  NEWCOMB,  U.  S.  N. 


REPORT    OF    PROFESSOR    NEWCOMB,    U.  S.  N. 


BERLIN,  March  21,  1871. 

COMMODORE  :  I  have  the  honor  to  present  the  following  report  of  my  observations  of  the  total  solar 
eclipse  of  December  22,  last,  made  in  compliance  with  the  orders  of  the  Honorable  Secretary  of  the  Navy. 
As  my  proceedings  were  necessarily  determined  by  the  character  of  the  observations  to  be  made,  I  ask  leave 
to  begin  by  calling  to  your  mind  the  plan  of  work  marked  out  for  me. 

The  great  number  of  spectroscopic  parties,  who  were  expected  to  take  part  in  the  observations,  made  it 
desirable  to  choose  some  less  occupied,  though,  it  might  be,  less  brilliant  field.  It  was  therefore  determined 
that  I  should  simply  scrutinize  the  physical  constitution  of  the  corona,  as  it  appeared  through  the  telescope 
employed  in  the  observations  of  partial  phase.  The  question  kept  more  particularly  in  mind  was  one 
respecting  which  the  testimony  of  previous  observers  is  very  discordant,  namely,  whether  there  is  any  appear- 
ance of  structure  in  the  formation  of  the  corona,  or  whether  its  different  parts  seem  to  run  into  each  other 
by  insensible  gradations ;  in  other  words,  whether  the  corona  is  composed  of  bright  points,  filaments,  and 
rays,  or  whether  its  light  is  soft  and  milky.  In  the  former  case,  it  would  be  proved  that  the  corona  could 
not  result  solely  from  an  elastic  atmosphere  surrounding  the  sun,  while  in  the  latter  this  question  might  still 
be  an  open  one. 

Another  object  was  to  determine,  with  as  much  accuracy  as  possible,  the  path  of  the  center  of  the 
shadow  over  the  surface  of -the  earth,  and  the  time  of  its  passing  a  given  point,  in  order  to  compare  these 
results  with  those  previously  calculated  from  the  lunar  tables,  and  thus  obtain  data  for  the  correction  of  the 
latter.  The  relative  positions  of  the  sun  and  moon  can  indeed  be  determined  by  observations  of  an  eclipse 
at  points  far  removed  from  the  central  line.  But  the  observations  for  this  purpose,  as  usually  made,  are  sub- 
ject to  various  unavoidable  sources  of  error,  which  it  is  not  necessary  to  enumerate.  On  the  other  hand, 
when  the  observer  is  on  or  near  the  line  of  central  eclipse,  observations  for  this  purpose  can  be  made  with 
great  precision,  and  my  -arrangements  were  planned  with  the  view  of  putting  in  practice  a  very  accurate 
method  of  observation,  which,  if  not  new,  has  fallen  into  almost  complete  desuetude.  This  method  is 
founded  on  the  geometrical  theorem  that  the  line  joining  the  cusps  of  the  partially  eclipsed  sun  is  at  right 
angles  to  the  line  joining  the  centers  of  the  sun  and  moon,  so  that  the  angle  of  position  of  the  latter  line 
can  be  immediately  inferred  from  that  of  the  former.  The  advantages  of  the  method  arise  from  the  great 
extent  to  which  the  errors  of  the  ordinary  class  of  observations  may  thus  be  diminished.  During  the  last 
century,  observations  of  solar  eclipses  have  been  generally  confined  to  determinations  of  the  times  of  con- 
tact of  the  limb  of  the  moon  with  that  of  the  sun  or  with  spots  on  its  surface.  The  latter  furnish  no  data  for 
fixing  the  position  of  the  moon,  because  the  positions  of  the  spots  are  never  accurately  known.  The  former 
generally  consist  of  observations  of  external  contact,  or  moments  of  the  beginning  and  end  of  the  eclipse. 
But  if  we  consider  the  question  with  mathematical  accuracy,  we  must  admit  that  an  actual  external  contact 
of  the  limb  of  the  moon  with  that  of  the  sun  cannot  be  observed,  because  the  former  cannot  be  seen  until 
it  has  impinged  on  the  latter  to  an  appreciable  extent.  If  the  magnitude  of  this  extent  were  constant,  it 
could  be  easily  determined  and  allowed  for.  But,  unfortunately,  it  is  a  very  variable  and  uncertain  element, 
depending  on  the  observer,  the  telescope,  and  the  nature  of  the  moon's  surface,  smooth  or  rough,  at  the  point 
of  contact.  Observations  of  last  contact  are  indeed  less  in  error  from  this  cause  than  those  of  first  .contact, 
but  they  still  exhibit  very  large  discrepancies. 

Observations  of  internal  contact  in  annular  and  total  eclipses  are  free  from  the  source  of  error  here  con- 
sidered. But  they  are  still  subject  to  the  uncertainties  arising  from  the  inequalities  of  the  moon's  surface  ; 
and  when  made,  as  is  usually  the  case,  at  points  near  the  line  of  central  eclipse,  they  afford  no  data  what- 
ever for  determining  the  error  of  the  moon's  latitude,  or  the  path  of  the  line  along  the  earth's  surface.  To 
be  useful  for  this  purpose,  observations  of  contact  must  be  made  at  points  near  the  limits  of  annular  or  total 
phase.  We  have-occasional  observations  so  made  at  public  or  private  observatories,  which  chanced  to  lie  in 
the  proper  position  relatively  to  the  moon's  shadow ;  but  I  know  of  only  two  total  eclipses  in  which  sys- 
tematic arrangements  were  made  to  determine  by  observation  the  path  of  the  moon's  shadow  along  the  sur- 


8  OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 

face  of  the  earth.  These  were  the  eclipses  of  1715,  in  which  the  moon's  shadow  passed  over  England,  and 
that  of  1869,  in  which  it  passed  over  the  United  States.  The  method  adopted  in  the  latter  was  substantially- 
identical  with  that  employed  by  Halley  in  the  former,  and  consisted  in  securing  observations  of  the  simple 
duration  of  total  phase  by  intelligent  inhabitants  at  various  points  near  the  limits  of  totality.  Though  this 
method  is  the  best  yet  used,  it  is  not  always  satisfactory  or  practicable.  The  limits  of  the  shadow  are  them- 
selves rendered  uncertain  by  the  irregularities  of  the  moon's  surface,  besides  which  we  require  an  accurate 
knowledge  of  the  positions  of  all  the  observers  before  the  observations  can  be  utilized.  Of  course  the 
observations  can  be  made  only  in  those  rare  cases  when  the  shadow  passes  over  a  well-populated  country. 
But  knowing  from  observation  the  angle  of  position  of  the  line  joining  the  center  of  the  sun  and  moon  at 
any  moment,  we  can  thence  infer  the  direction  of  the  center  of  the  shadow  at  that  moment.  By  making  a 
number  of  determinations  of  this  angle,  as  seen  from  any  point  in  or  near  the  shadow  while  the  latter  is  pass- 
ing, the  path  of  its  center  can  thence  be  inferred  with  great  accuracy.  It  is  true  that  the  error  of  any 
isolated  measure  arising  from  inequalities  of  the  moon's  surface  will  be  of  the  same  magnitude  with  that  of 
an  observed  contact.  But  all  the  measures  being  made  on  different  parts  of  the  moon's  contour,  as  the 
solar  crescent  seems  to  move  around  the  moon,  the  errors  arising  from  irregularity  of  contour  will  be  almost 
entirely  eliminated  from  the  mean  result.  My  trial  of  this  method  convinces  me  that  the  observations  of 
the  sharp  cusps  can  be  made  with  even  greater  precision  than  I  had  anticipated. 

The  direct  determination  of  the  line  joining  the  cusps  is,  however,  scarcely  practicable,  owing  to  the 
breadth  of  the  solar  disk,  which  prevents  the  observer  from  setting  a  wire  simultaneously  on  the  two  cusps, 
unless  the  telescope  be  moved  by  clockwork  and  a  low  power  be  used.  We  have  therefore  to  substitute 
differences  of  right  ascension  of  the  cusps,  which  may  be  obtained  by  observing  transits  of  the  two  cusps 
over  the  wires  of  an  equatorially  mounted  telescope.  This  was  the  mode  of  observation  actually  adopted, 
the  telescope  employed  being  the  comet-seeker  of  the  Observatory.  The  instrumental  arrangements  will  be 
more  fully  described  in  connection  with  my  observations,  which  I  shall  preface  with  an  account  of  the  pre- 
liminary operations  made  to  secure  the  success  of  the  proposed  plan. 

I  sailed  from  New  York,  in  compliance  with  my  orders,  and  reached  London  on  November  ist.  My 
instructions  left  me  at  liberty  to  select  that  point  along  the  line  of  totality  the  longitude  of  which  could  best 
be  determined  by  the  electric  telegraph,  an  accurate  longitude  being  required  before  my  observations  could 
be  used.  Immediately  on  my  arrival  in  London  I  therefore  sought  an  interview  with  the  Astronomer  Royal, 
to  confer  with  him  respecting  the  choice  of  a  station,  and  to  request  his  co-operation  in  the  work  of  deter- 
mining the  longitude  of  such  station  as  might  be  selected.  It  was  soon  found  that  Gibraltar  was  in  this 
respect  the  most  favorable  point  along  the  path  of  totality,  as  it  was  in  direct  telegraphic  communication 
with  England  through  the  Falmouth,  Gibraltar  and  Malta  cable.  The  Astronomer  Royal  entered  into  my 
plans  in  the  most  obliging  manner,  agreeing  to  send  time-signals  from  the  Royal  Observatory  to  my  station 
whenever  the  two  points  could  be  put  in  telegraphic  communication,  and  using  his  influence  to  secure  such  com- 
munication. To  attain  this  end,  he  introduced  and  recommended  me  to  the  engineer-in-chief  of  the  govern- 
ment telegraphs,  R.  S.  Culley,  Esq.  Mr.  Culley  most  cordially  tendered  us  the  use  of  any  of  the  telegraph 
lines  that  might  be  under  his  control.  It  only  remained  to  ask  for  the  use  of  the  cable,  and  this  I  did  in  con- 
junction with  Mr.  G.  W.  Dean  of  the  Coast  Survey,  who  had  been  instructed  by  Professor  Peirce  to  co-operate 
with  our  parties  whenever  the  interests  of  science  could  be  so  advanced,  and  whose  experience  in  telegraphing 
longitude-signals  through  the  ocean-cables  made  his  counsel  of  great  value.  We  arranged  for  an  interview 
with  Sir  James  Anderson,  managing  director  of  the  cable,  on  the  following  Monday.  At  this  interview,  the 
distinguished  director  expressed  the  great  pleasure  it  would  give  him  to  do  everything  in  his- power  to  insure 
the  success  of  our  observations,  and  offered  to  place  the  cable  at  our  disposal  at  such  times  as  we  might 
require  it  for  the  transmission  of  signals.  As  the  cable  was  least  loaded  with  business  on  Sunday  afternoons 
and  Monday  mornings,  it  was  agreed  to  select  these  times  for  transmission  if  weather  permitted  of  our 
correcting  our  chronometers  by  astronomical  observations. 

It  only  remained  to  frame  a  plan  of  operations  for  the  transmission  of  signals,  which  I  did,  after  consul- 
tation with  the  Astronomer  Royal  and  Mr.  Dean.  The  unfortunate  failure  of  the  scheme  through  a  cause 
beyond  human  foresight  and  control  deprives  both  my  plan  and  my  further  proceedings  under  it  of  nearly 
all  their  interest.  However,  I  inclose  a  copy  of  the  plan  as  evidence  of  the  care  with  which  the  operations 
were  arranged.  To  guard  as  far  as  possible  against  all  possibility  of  failure,  Sir  James  Anderson  advised  me 
to  visit  the  telegraph  office  at  Porthcurno,  the  terminus  of  the  cable,  and  assure  myself  that  all  the  arrange- 
ments for  transmitting  signals  were  properly  made  and  understood  by  the  operators.  I  started  on  this  journey 


REPORT  OF  PROFESSOR  NEWCOMK  9 

December  2cl,  and  on  the  very  same  day  I  was  advised  that  a  fault  had  occurred  in  the  cable  between  Lisbon 
and  Gibraltar.  As  it  was  expected  that  the  fault  would  be  speedily  found  and  repaired,  I  made  no  change 
in  my  plan  of  operations,  and  completed  the  proposed  journey.  The  hope  in  question  was,  however,  not 
realized,  so  that  no  time-signals  could  be  transmitted  at  all.  The  failure  of  the  cable  at  this  moment  was 
most  unfortunate  for  us,  because,  had  I  not  fully  expected  to  obtain  a  telegraphic  longitude,  I  should  have 
tried  to  organize  a  chronometric  expedition  for  the  same  purpose,  and,  I  believe,  would  have  succeeded. 
But  it  was  now  too  late  to  do  so ;  indeed,  I  did  not  return  to  London  at  all  after  my  visit  to  Penzance. 

During  my  stay  in  London  a  joint  committee  of  the  Royal  and  Royal  Astronomical  Societies  was  engaged 
in  organizing  an  expedition  for  the  observation  of  the  eclipse.  Having  secured  from  their  government  the 
grant  of  a  ship,  they  invited  me  to  accompany  them  to  Gibraltar.  I  accepted  this  flattering  invitation,  and 
therefore  proceeded  from  Porthcurno  direct  to  Portsmouth,  the  port  of  departure.  We  sailed  on  Tuesday, 
December  6th,  in  H.  B.  M.  Ship  Urgent,  on  which  I  was,  during  a  week,  the  guest  of  the  English  expedition. 
We  reached  Gibraltar,  after  a  rough  passage,  on  the  morning  of  December  i4th. 

I  first  called  on  the  American  consul,  H.  J.  Sprague,  Esq.,  and  made  known  to  him  the  object  of  my 
visit.  He  informed  me  that  my  instruments,  which  had  been  forwarded  by  the  consul  at  Liverpool,  had 
arrived  in  safety.  I  then  called  on  Mr.  De  Sauty,  superintendent  of  the  Gibraltar  office  of  the  telegraph 
company,  and  learned  that  Professor  Hall  was  awaiting  me  at  Malta  in  order  to  exchange  time-signals.  I 
arranged  for  the  exchange  on  the  two  following  days. 

The  business  next  in  order  was  to  make  the  object  of  my  visit  known  to  the  authorities.  Accordingly, 
on  Friday,  Mr.  Sprague  presented  me  to  His  Excellency  Sir  W.  F.  Williams,  of  Kars,  the  governor  of  the 
fortress,  who  most  obligingly  tendered  me  every  facility  in  his  power  for  making  my  observations  from  any 
station  I  might  select  within  his  jurisdiction.  The  selection  of  a  station  was,  however,  no  easy  matter. 
None  of  the  authorities  I  consulted  advised  a  point  within  the  town,  for  the  reason  that  during  an  east  wind 
the  latter  is  always  covered  with  fog,  though  the  sky  may  be  clear  both  to  the  north  and  the  south.  A  station 
far  enough  north  to  avoid  this  evil  would  be  on  Spanish  soil  .and  would  be  subject  to  several  inconveniences, 
one  of  which  would  be  the  impossibility  of  any  communication  with  the  telegraph  office  or  the  town  at  night- 
A  station  to  the  south  was  objectionable  because  farther  removed  from  the  line  of  central  eclipse,  which 
passed  some  twenty  miles  north  of  Gibraltar.  As  this  seemed  to  be  the  least  of  the  evils,  I  selected  a  point 
known  as  Buena  Vista,  about  half-way  between  the  town  and  Europa  Point.  Its  position  relatively  to  some 
other  points  in  the  fortress  was  as  follows,  the  distances  being  given  in  round  hundreds  of  feet,  as  measured 
on  a  large  map  :* 

8,800  feet  south  and  1,400  feet  east  of  telegraph  office. 

6,900  feet  south  and  800  feet  east  of  American  consul's  house,  Edward's  Road. 

5,600  feet  south  and  1,100  feet  west  of  Signal  Tower. 

2,700  feet  south  and  2,000  feet  east  of  base  of  new  mole. 

v  • 

According  to  the  Admiralty  Chart  of  1864,  the  position  of  the  flag-staff  near  the  latter  point  is  latitude 
36°  7'  10";  longitude  o1'  21'"  25". i  W.t  This  would  make  the  position  of  my  station 

Latitude,  36°  6'  43"  N. 
Longitude,  o1'  21'"  238.4  W. 

The  latitude  derived  from  my  sextant  observations  is 

36°  6'  5  i", 

with  a  probable  error  of  four  or  five  seconds.  The  difference  of  eight  seconds  is  quite  unimportant  in  the 
case  of  the  eclipse  observations. 

Having  signified  my  choice  01  a  station  to  the  governor,  his  excellency  immediately  directed  that  1 
should  be  supplied  with  anything  in  the  shape  of  military  stores  I  might  require.  I  thus  received  everything 
necessary  for  the  protection  ot  my  instruments,  including  tents  and  a  guard. 

The  instruments  were  conveyed  to  the  station  on  Saturday,  and  the  work  of  getting  them  into  position 
was  commenced  on  Monday.  They  consisted  of  the  observatory  comet-seeker,  which  was  fitted  up  fcr 
the  observation  of  the  eclipse  itself;  a  small  portable  transit,  by  Wiirdemann,  of  about  two  inches  aperture, 

*  There  is  probably  an  error  of  about  5°  in  azimuth  in  these  measures,  the  direction  of  the  supposed  meridian  being 
really  N.  5°  W.  and  S.  5°  E. 

f  The  chart  of  July  27,  1869,  gives  a  longitude  2s  lessi 
2— E 


IO 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


made  for  the  Northwestern  boundary  survey,  and  loaned  to  the  expedition  by  the  Chief  of  Engineers  of  the 
Army.     For  the  determination  of  latitude  and  time  I  had  also  a  Gambey  sextant  with  artificial  horizon. 

The  comet-seeker  is  an  equatofially  mounted  telescope,  of  thirty-two  inches  focus  and  four  inches 
aperture.  When  turned  on  the  sun  the  aperture  has  to  be  reduced  to  two  inches  or  less,  owing  to  the  inten- 
sity of  the  heat  concentrated  at  the  eye-end  when  the  full  aperture  is  used.  Its  small  size  is  partly  compen- 
sated for  by  its  fine  definition.  A  power  of  forty  was  selected  for  the  observation  of  the  eclipse.  The  eye- 
piece was  furnished  with  a  diaphragm  of  eleven  vertical  and  four  horizontal  wires,  arranged  as  in  the  accom- 
panying diagram,  by  Mr.  Gardner,  instrument-maker  at  the  United  States  Naval  Observatory.  The  intervals 
between  the  closer  vertical  wires  are  approximately  each  2*<£'  of  arc,  or  10"  of 
time,  while  the  wider  intervals  on  each  side  of  the  center  wire  are  5'  of  arc. 
The  extreme  distance  between  the  outside  wires  is  therefore  30',  or  a  little 
less  than  the  Sun's  diameter.  The  eye-piece  could  be  turned  into  any  re- 
quired position,  so  that  the  term  vertical,  as  applied  to  the  eleven  wires,  is  only 
a  relative  one.  A  notch  was  cut  into  the  eye-piece  to  indicate  a  fixed  posi- 
tion of  the  latter  in  which  the  central  wire  coincided  accurately  with  the 
meridian  of  the  instrument.  There  was  no  other  means  of  fixing  or  deter- 
mining the  angle  of  position  of  the  wires.  The  direction  of  the  polar  axis  of 
the  instrument  admitted  of  no  adjustmenr  for  latitude;  but  Gibraltar  being  less 
than  three  degrees  south  of  Washington,  it  was  easy  to  elevate  one  side  ot 
the  base  of  the  instrument  enough  to  secure  the  adjustment  in  question.  Both  axes  of  the  instrument 
have  divided  circles,  and  each  circle  is  read  by  two  opposite  verniers,  which  give  single  minutes  in  dec- 
lination and  spaces  of  four  time-seconds  in.R.  A. 

The  transit-instrument  was  mounted  on  a  cast-iron  stand.  For  the  adjustment  of  level  and  azimuth 
one  Y  was  movable  horizontally  and  the  other  vertically.  Both  movements  were  effected  by  micrometer- 
screws  with  divided  heads,  a  feature  very  convenient  for  the  determination  of  the  instrumental  constants. 
The  reticule  consisted  of  seven  vertical  and  two  horizontal  wires.  The  instrument  was  supplied  with  two 
spirit-levels  for  leveling  the  axis. 

As  it  was  not  easy  to  get  solid  stone  piers  for  the  instrument,  I  adopted  the  plan  of  using  the  outside 
packing-cases,  well  packed  with  sand,  for  the  supports.  For  the  transit  the  box  was  packed  slightly  more 
than  full,  so  that  when  the  top  was  nailed  down  its  upper  surface  was  rendered  slightly  convex  by  the  pres- 
sure of  the  sand  below.  The  stability  of  the  instrument,  though  ample  to  determine  the  local  time  for  obser- 
vation of  the  eclipse,  would  not  have  sufficed  for  any  accurate  astronomical  determination.* 

The  comet-seeker  was  mounted  under  a  tent  in  such  a  way  that  by  slightly  changing  the  position  of  the 
latter  through  its  supporting  cords  the  instrument  could  be  either  entirely  covered  in,  or  could  be  left  far 
enough  out  to  command  the  southern  half  of  the  heavens.  On  the  day  preceding  the  eclipse  I  got  it  ad- 
justed to  the  diurnal  motion  of  the  earth  as  nearly  as  seemed  practicable  with  the  rough  means  at  my  disposal. 
The  reticule  was  adjusted  on  a  distant  object,  so  that  the  middle  right  ascension  wire  was  as  nearly  as  pos- 
sible in  the  plane  of  motion  of  the  instrument  in  declination;  after  the  adjustment  was  made,  however,  the 
top  of  the  wire  seemed  to  incline  to  the  east  by  the  smallest  appreciable  amount.  In  the  day  and  evening 
observations  were  made  to  determine  such  of  the  instrumental  errors  as  it  was  necessary  to  know.  During 
this  entire  day  the  sky  was  cloudless,  and  everything  gave  promise  of  a  fine  day  for  the  eclipse. 

The  morning  of  the  22d  dawned  with  equal  promise.  At  8  o'clock  only  a  few  light  and  fleecy  clouds 
were  to  be  seen  in  the  sky.  A  little  before  nine  I  observed  the  transit  of  ,9  Ursae  Minoris  with  the  transit 
instrument.  But  before  I  could  get  another  observation  clouds  began  to  cover  the  sky,  and  an  hour  before 
the  time  of  commencement  of  the  eclipse  the  southern  heavens  were  covered  with  clouds,  mist,  and  fog, 
which  came  in  from  the  Atlantic'.  There  was  still  much  blue  sky  to  be  seen  in  the  north,  so  that  I  thought 
I  should  have  done  better  to  observe  from  the  town.  In  another  half  hour  this  had  also  disappeared,  the 
instruments  had  to  be  covered  to  protect  them  from  the  rain,  and  the  prospect  seemed  hopeless.  But  a 
short  time  before  the  commencement,  fugitive  glimpses  of  the  sun  began  to  be  obtained  through  the  clouds. 
I  took  my  seat  at  the  telescope  and  got  a  very  good  view  of  first  contact  at  22"'  52™  35",  chronometer  time. 

~  "  To  each  error  of  one  second  in  the  determination  01  time  would  correspond  an  error  of  o"-4  in  the  longitude  of  the  moon 
deduced  from  the  observation.  The  instrument  was  steady  enough  to  give  the  local  time  certainly  within  a  fourth  of  a  second, 
so  that  the  deduced  longitude  of  the  moon  could  not  be  o".  I  in  error  from  this  cause. 


REPORT  OF  PROFESSOR  NEWCOMH.  !  i 

This  was  the  moment  at  which  [  began  to  see  the  limb  ot  the  sun  indented  by  the  rough  edge  of  the  moon. 
The  actual  first  contact  must  have  occurred  an  appreciable  time,  probably  two  or  three  seconds,  sooner.  I 
then  turned  the  eye-piece  so  that  the  R.  A.  wires  of  the  eye-piece  were  at  right  angles  to  the  chord  of  the 
eclipsed  portion  of  the  sun,  and  noted  the  moments  at  which  the  length  of  the  chord  was  measured  by  certain 
wire  intervals.  These  observations  were  rendered  difficult  and  uncertain  by  the  flying  clouds,  which  would 
at  one  moment  shut  the  sun  off  entirely  and  at  another  suddenly  let  him  shine  with  full  brilliancy.  How- 
ever, I  give  the  observations  ///  fxfat.w  in  the  accompanying  papers. 

Again  the  sun  was  completely  hidden,  and  again  the  instruments  had  to  be  covered  from  the  drizzling 
rain.  Half  an  hour  before  the  total  phase,  when  I  wanted  to  measure  the  cusps,  the  clouds  again  partially 
cleared  away,  so  that  I  was  able  to  obtain  several  sets  of  transits  of  the  cusps  over  the  R.  A.  wires  of  the 
comet-seeker  between  and  through  the  rapidly  driving  clouds.  For  this  purpose,  the  eye-piece  was  restored 
to  its  vertical  position  by  the  notch  made  for  that  purpose. 

During  the  five  minutes  preceding  the  total  phase  the  prospect  of  seeing  the  latter  looked  as  dark  as 
ever.  Once  more,  however,  the  clouds  broke  up  at  the  critical  moment.  A  minute  or  two  before  the  dis- 
appearance of  sunlight,  what  little  was  left  of  the  sun  appeared  through  the  clouds,  and  I  again  turned  the 
eye-piece  so  as  to  measure  with  the  R.  A.  wires  the  length  of  the  vanishing  crescent,  having  first  removed 
the  cap  from  the  telescope  so  as  to  see  with  the  full  aperture  of  four  inches.  But  in  the  hurry  and  confusion 
of  the  moment  I  did  not  get  a  measure.  I  noticed,  however,  that  when  the  crescent  was  reduced  to  about 
90°,  the  ends  began  to  break  off  and  disappear.  This  process  went  on  with  increasing  rapidity  until  oh  i8m  35s 
chronometer,  when  all  that  remained  of  the  crescent  was  broken  up  throughout  its  entire  length.  The  fragments 
thus  formed  disappeared  one  by  one,  and  the  last  one  vanished  at  oh  i8m  37".  I  judge  that  the  true  time  of 
second  contact  should  be  considered  about  the  mean  of  these  two  moments,  or  oh  18'"  36". 

As  soon  as  I  had  recorded  the  time  of  disappearance  I  put  my  eye  again  to  the  telescope.  Instead  ot 
the  gorgeous  spectacle  I  witnessed  in  1869,  I  saw  only  the  most  insignificant  corona,  although  the  full 
aperture  of  the  telescope  was  used.  Supposing  that  this  was  of  course  due  to  the  clouds,  I  kept  my  eye  at 
the  telescope  in  hopes  of  their  disappearance,  still,  however,  scrutinizing  the  phenomena  most  carefully.  I 
could  not  see  the  slightest  trace  of  bright  or  dark  points,  rays,  or  filaments,  the  light  everywhere  seeming  as 
soft  and  diffused  as  the  zodiacal  light.  There  were,  indeed,  as  in  former  eclipses,  great  differences  between 
the  extent  and  brilliancy  of  the  corona  at  different  points,  but  all  the  parts  seemed  to  shade  into  each  other  by 
insensible  gradations.  The  protuberances  on  the  eastern  limb  of  the  sun  were  numerous  and  brilliant,  pre- 
senting the  many  fantastic  forms  which  photography  has  rendered  so  familiar.  Rut  they  presented  no 
appearance  of  structure,  as  did  the  great  protuberance  in  the  eclipse  of  1869.  The  light  and  color  of  all 
were  sensibly  uniform  throughout  their  entire  extent,  and  their  outline  was  sharply  defined.  So  far  as  I  saw 
they  were  all  of  the  red  color  so  frequently  described,  a  much  brighter  red  than  I  saw  at  Des  Moines.  I 
cannot  speak  for  minute  differences  of  color  or  brilliancy,  because  I  had  not  intended  to  make  the  protuber- 
ances a  special  object  of  scrutiny. 

I  waited  in  vain  through  the  few  moments  of  total  eclipse  for  the  corona  to  be  seen  more  distinctly,  and 
observed  the  reappearance  of  sunlight  under  the  impression  that  the  clouds  had  prevented  me  from  seeing 
more  than  a  very  little  of  the  corona.  But,  after  finishing  my  observations,  Mr.  Sprague  and  Mrs.  Newcomb, 
both  of  whom  were  outside  of  my  tent,  agreed  in  testifying  that  the  sky  in  the  direction  of  the  sun  seemed 
quite  free  from  clouds  during  the  entire  total  phase,  and  that  two  stars  were  distinctly  visible  in  the  neighbor- 
hood of  the  sun.  It  is  a  little  singular  that  while  the  two  parties  agree  in  describing  the  positions  of  the 
stars,  their  descriptions  are  not  reconcilable  with  the  positions  of  Venus  or  Saturn,  the  only  bright  planets  in 
the  neighborhood  of  the  sun.  I  bring  this  forward  as  tending  to  excite  suspicion  that  the  corona  is  subject 
to  very  great  changes  of  brilliancy,  a  suspicion,  however,  which  can  be  removed  or  confirmed  only  by  the 
observations  of  others.  My  own  testimony  is  simply  this :  the  corona  of  1869,  through  a  haze  which  ren- 
dered all  but  the  brightest  stars  invisible  to  the  naked  eye,  seemed  to  me  many  times  more  brilliant  than  that 
of  1870,  seen  through  an  atmosphere  which  permitted  at  least  the  brighter  planets  to  be  seen. 

The  first  ray  of  returning  sunlight  appeared  at  oh  20™  27",  chronometer.  It  appeared  at  several  points 
of  the  moon's  limb  in  such  rapid  succession  that  I  could  not  designate  an  exact  moment  in  which  the  crescent 
seemed  broken  up  as  it  did  2s  before  the  disappearance  of  sunlight.  During  the  succeeding  minute 
I  succeeded  in  getting  three  measures  of  the  length  ot  the  crescent,  but  they  were  by  no  means  satisfactory. 

I  then  set  the  eye-piece  into  position  for  observing  transits,  and  during  the  hall  hour  following  observed 
nine  sets  of  transits  very  satisfactorily  indeed.  Clouds  as  thick  as  ever  then  intervened,  but  cleared  away 


12 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22.  1870. 


again  in  time  to  allow  or  a  very  satisfactory  set  ot  measures  of  chord  during  the  few  minutes  preceding  the 
last  contact,  and  of  the  observation  of  last  contact. 

The  failure  of  the  longitude  determination  prevents  me  from  giving  a  definitive  reduction  of  my  observa- 
tions. I  have  no  knowledge  of  the  manner  in  which  the  Admiralty  longitude  already  quoted  was  determined, 
or  whether  it  is  sufficiently  accurate  for  astronomical  purposes.  Assuming,  however,  that  this  longitude  is 
correct,  the  computed  and  observed  times  of  the  phases,  and  the  resulting  errors  of  the  difference  of  tabular 
longitudes  of  the  sun  and  moon,  will  be  as  follows : 


Phase. 

Greenwich  times. 

Local  times. 

Obs.  times. 

A  / 

V 

A  > 

h.     m.       s. 

h.     m.       s. 

s. 

s. 

,, 

First  contact    .    . 

22     51     38.6 

22     30     15.2 

13-4 

-     i.S 

+     0.7 

Second  contact  .. 

o     17     40  .  S 

23     56     17-4 

M.4 

3-0 

+      i.i 

Third  contact  .    . 

o     19   '29.8 

23     58      6.4 

5-4 

I.O 

+     0.4 

Fourth  contact    . 

I     46     47.6 

i     25     24.2 

18.4 

5-8 

+       2.2 

This  result  would  indicate  a  correction  of  +1"-1  l«  the  longitude  of  the  moon  derived  from  Peirce's 
tables,  supposing  Hansen's  tables  of  the  sun  to  be  correct.  Comparing  Hansen's  lunar  with  Le  Verrier's  solar 
tables,  the  relative  correction  will  be  — 6".4,  an  amount  which  I  can  scarcely  believe  the  error  of  Hansen's 
tables  have  reached. 

In  the  accompanying  papers  I  present  the  observations  ///  exti-nsv,  with  such  preliminary  reductions  as 
I  have  been  able  to  make.  They  ure  as  follows : 

A.  The  observed  times  of  contact  and  the  measures  of  chords  near  these  times,  which  may  serve  to 
correct  the  latter. 

B.  The  observed  transits  of  the  cusps  over  the  wires  of  the  comet-seeker,  made  to  determine  the  differ- 
ence of  their  right  ascensions.     To  reduce  these  observations  completely  it  is  necessary  to  know  the  angle 
which  the  line  of  motion  of  the  instrument  at  any  point  makes  with  the  meridian.     This  requires  a  knowledge 
of  four  constants,  the  errors  of  collimation  of  the  two  axes  of  the  instrument,  and  the  hour  angle  and  polar 
distance  of  the  point  in  the  heavens  toward  which  the  polar  axis  of  the  instrument  is  directed.     The  obser 
vations  for  this  purpose  are  given  in  C. 

D.  The  sextant  observations  for  latitude  of  station,  with  a  summary  of  the  resulting  values  of  the  latitude. 
The  error  of  eccentricity  of  the  sextant  being  uncertain,  a  much  greater  weight  has  been  given  to  the  results 
of  those  dates  when  a  north  and  south  object  were  both  observed. 

E.  Sextant  observations  for  correction  of  chronometer,  made   before  the   mounting  of  the  transit, 
completely  reduced.     The  result  of  December  i6th  is  discordant  to  a  degree  I  cannot  account  for ;  it  is  difficult 
to  suppose  such  a  change  to  have  actually  taken  place  in  the  error  of  the  chronometer. 

F.  Observations  for  index  correction  of  sextant. 

G.  Transits  observed  with  the  transit-instrument,  completely  reduced. 

H.  The  observations  for  determining  the  constants  pertaining  to  the  transit-instrument. 
I.   Kxchange  of  signals  with  Professor  Hall  at  Malta,  through  the  Falmouth,  Gibraltar  and  Malta  cable. 
A  determination  of  the  inclination  of  the  separate  wires  of  the  comet-seeker  is  still  wanting  for  the  com- 
plete reduction  of  the  transits  of  cusps,  and  the  definitive  determination  of  the  path  of  the  center  of  the  shadow. 
This  cannot  be  done  till  my  return,  when  I  hope  to  present  you  with  the  definitive  results  of  my  observations. 
It  has  been  my  agreeable  duty,  both  in  this  and  in  my  preceding  reports,  to  inform  you  of  the  numerous 
facilities  and  courtesies  extended  to  me  by  the  authorities  of  Great  Britain.     I  have  only  to  add,  in  general 
terms,  that  nothing  could  exceed  the  cordial  and  friendly  spirit  with  which  the  objects  of  our  expedition  were 
everywhere  received  and  promoted  by  all  the  authorities  and  people  of  that  country  with 'whom  it  was  my 
good  fortune  to  come  into  contact.     It  is  also  just  that  I  should  acknowledge  the  indebtedness  of  the  expedi- 
tion to  Mr.  Horatio  J.  Sprague,  United  States  consul  at  Gibraltar,  for  his  many  exertions  to  secure  its  success. 
Very  respectfully,  your  obedient  servant, 

SIMON  NEWCOMB, 
Professor  of  Mathematics,  U.  S.  N. 
Commodore  B.  F.  SANDS,  U.  S.  N., 

Superintendent  U.  S.  Naval  Observatory,  Washington. 


REPORT  OF  PROFESSOR  NEWCOMB.  13 

A. 

Observed  chronometer  times  of  contact,  and  distances  of  cusps  near  the  times  of  contact. 
Chronometer  times. 


b. 

m. 

S. 

22 

52 

35 

First 

contact. 

22 

53 

55-° 

Chord    reaches 

from    wires 

iv  j4 

to 

VI. 

22 

54 

47^ 

u 

u 

"          " 

IV 

to 

VI. 

22 

55 

31.0 

tt 

" 

a          tt 

IIIi4 

to 

VI. 

22 

57 

5o: 

tt 

" 

tt          tt 

IV>£ 

to 

VII. 

2  2 

58 

58: 

" 

(t 

tt          tt 

IV 

to 

VII. 

O 

18 

35 

The 

small  remaining  crescent 

broken  up  by  the  rough  edge  of  the  moon  throughout 

its 

entire  length. 

O 

18 

37 

The 

last  point  of  sunlight  vanishes. 

O 

20 

27 

Light  reappears. 

0 

20 

55 

Crescent  extends 

from  wires 

V 

to 

XI. 

0 

21 

1  1 

' 

t             tt 

it         tt 

III 

to 

XI. 

O 

21 

29 

i 

i             a 

tt         tt 

I# 

to 

XI. 

I 

40 

5° 

Chord    reaches 

from    wires 

V 

to 

VIII. 

I 

42 

16 

" 

" 

tt          tt 

IVi^ 

to 

VII. 

I 

43 

25 

" 

" 

tt          tt 

V 

to 

VII. 

I 

44 

35^ 

" 

tt 

it                   tt 

111% 

to 

VI. 

I 

45 

17 

" 

" 

tl                   tl 

IV 

to 

VI. 

I 

46 

8 

tt 

" 

tt                   tt 

iv>^ 

to 

VI. 

I 

46 

34^ 

tt 

" 

tt                   tt 

V 

to 

VI. 

I 

47 

6>2 

It 

tt 

It                   tt 

III^ 

to 

V. 

I 

47 

27 

tt 

it 

tl                   It 

IV 

to 

V. 

I 

47 

40 

Last 

contact. 

NOTE. — The  measures  of  chord  following  first  contact  were  rendered  difficult  and  uncertain  by  the  continual  passage  01 
flying  clouds. 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


B. 

Transits  of  the  sun's  cusps  over  the  R.  A.  wires  of  the  comet-seeker  to  determine  the  difference  of  their  right 
ascension,  and  thence  their  angle  of  position  and  the  angle  of  position  of  the  line  joining  the  centers  of  the 
sun  and  moon. 

(Telescope  east  of  axis.) 


Cusp. 

I. 

II. 

III. 

IV. 

V. 

VI. 

VII. 

VIII. 

IX. 

X. 

XI. 

h.   m. 

S. 

s. 

s. 

s. 

s. 

s 

S. 

N. 

23  50 
23  51 

59-3 
20.6: 

55-5 

42.9 

. 

28.5 

52.5 

14-5 

2-5 
26.0 

36.5 

S. 

23  54 

30.5 

41.0 

2-5 

. 

II.  0 

. 

32.5 

N. 

23  54 

52.3 

14.0 

27.0 

•  • 

. 

23.8 

' 

45-3 

56.3 

7-5 

S. 

23  58 

17-5 

28.3 

50.0 

23.8 

48.0 

59-o 

21  .O 

N. 

23  58 

40.5 

..   . 

3-3 

12.6 

•   • 

34-5 

45-5 

56.5 

S. 

O    I 

31-0 

41-7 

, 

. 

14.5 

38.0 

0.5 

".3 

44-5 

N. 

0    I 

55-0 

•  •' 

29.2 

25.5 

•   • 

59.0 

10.  0 

S. 

N. 

o   4 

o   5 

36.5 
i  .5 

47-5 

23.8 

9-2 

43-7 

6.5 

T2  8 

I/.5 

6  o 

51.0 

S. 

o   7 

43-5 

54-4 

5.0 

50-3 

13-3 

24.0 

N. 

o   8 

' 

20.8 

31.8 

41-3 

3-0 

14-5 

26.0 

S. 

O   IO 

46.8 

57.5 

8.5 

31.0 

17.5  : 

28.5 

39-5 

2.3 

N. 

0   II 

15.0 

38.0 

50.0 

0.8 

48.5 

"•5 

23.0 

35-0 

REPORT  OF  PROFESSOR  NEWCOMB.  15 

The  eye-piece,  with  the  diaphragm,  was  now  turned  back  90°,  to  observe  the  length  of  the  small  remain- 
ing crescent  of  the  sun  during  the  minute  preceding  the  total  phase. 

After  the  total  phase,  it  was  returned  (as  was  supposed)  accurately  to  its  original  position,  and  the  transits 
of  the  cusps  were  again  observed,  as  follows  : 

At 


the  line  joining  the  cusps  was  parallel  to  the  R.  A.  wires. 


Cusp. 

I. 

II. 

III. 

IV. 

V. 

VI. 

VII. 

VIII. 

IX. 

X. 

XI. 

S. 
N. 

h.  m. 
o  25 

o  27 

S. 

49.0 

s. 

s. 

s. 

22.0 

s. 

s. 

s. 

20.2 

s. 

42.0 

s. 

s. 
4-5 

S. 

o  28 

49-7 

11.5 

33-8 

55-7 

19.5 

41.3 

4.0 

N. 

o  29 

O.2 

22.8 

•   • 

45-7 

9.0 

32.4 

54-2 

16.8 

S. 

o  31 

42.1 

3-7 

26.0 

49-4 

H.  8 

33-6 

56.0 

N. 

o  31 

54-3 

16.6 

39-5 

2-5 

25.5 

47-3 

9-5 

S. 

o  34 

31.4 

52.9 

15-3 

38.3 

I.O 

.  . 

23-3 

45.6 

N. 

o  34 

44-2 

•  • 

6.5 

29.2 

52.4 

15-3 

36.8 

59-5 

S. 

o  37 

24.7 

, 

46.8 

. 

8.6 

31.5 

54-5 

27.6 

N. 

o  37 

37-7 

•   • 

0.5 

23.0 

46.3 

9-2 

41.9 

•  • 

S. 

o  40 

8.7 

30-3 

. 

52.5 

15.3 

38.1 

0.0 

. 

22.0 

N. 

o  40 

22.  0 

44-0 

6.6 

29.8 

52.1 

14.0 

36.2 

S. 

o  42 

50.5 

. 

12.4 

. 

34-5 

57-5 

2O.  2 

41.9 

. 

4-5 

N. 

°  43 

4.2 

26.4 

49.1 

12.0 

34-7 

56.4 

18.5 

S. 

P  45 

51-5 

t 

12.9 

34-9 

57-8 

2O.9 

• 

42.0: 

5-0 

N. 

o  46 

4.6 

27.2 

49-5 

12.5 

35-4 

57.0 

19.4 

S. 

o  48 

41.2 

. 

2.8 

25.0 

47-5 

10.5 

> 

32.0 

54-5 

N. 

o  48 

54-5 

16.8 

39-0 

2.0 

25.0 

46.2 

•  • 

8.5 

'  It  was  now  found  that  after  the  total  phase  the  eye-piece  was  not  returned  accurately  to  its  original 
position.  While,  before  the  total  phase,  the  middle  R.  A.  wire  was  very  nearly  parallel  to  the  line  of  motion 
of  the  telescope  in  N.  P.  D.,  it  was  now  found,  by  observation  on  a  distant  terrestrial  mark,  that  the  top  of 
the  middle  wire  deviated  to  the  east  by  an  amount  which  throughout  the  breadth  of  the  field  (about  i°) 
amounted  to  1  the  distance  of  the  closer  wires,  or  about  if,  making  the  change  of  inclination  about  o°  16'. 
The  probable  error  of  this  estimate  is  about  ^  its  amount. 


i6 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870, 


C. 

Readings  of  circles  when  telescope  is  pointed  on  terrestrial  marks  in  reversed  positions  of  the  instrument,  watte  to 
determine  the  collimation  envrs  of  the  telescope  and  the  declination  axis,  and  the  index  error  of  the  declination- 
circle. 


Mark. 

Readings  of  declina- 
tion —  Verniers. 

Readings  of  R.  A.  — 
Verniers. 

Mean  Vernier. 

I. 

II. 

I. 

II. 

Dec. 

R.  A. 

0              / 

0              / 

h.  m.   s. 

h.  m.   s. 

0              / 

h.  m.  s. 

First  mark   .... 

314  58 

135  47 

9  47  22 

"21    48    12 

315    22 

9  47  47 

Tel.  reversed   .    .    . 

224  30 

45  24 

21  47  44 

9  47  24 

224  57 

21  47  34 

Second  mark  .    .    . 

308     o 

128  56 

10    17      2 

22    IS      0 

308  28 

10  17  31 

Tel.  reversed   .    .    . 

231   18 

52  16 

22    17   46 

10  18  18 

231  47 

22    IS      2 

Third  mark  .... 

8    22 

189  15 

IS  25   18 

6  25  42 

8  48 

18  25  30 

Tel.  reversed   .    .    . 

171    o 

35i  52 

6  26  26 

18    27    22 

171  26 

6  26  54 

These  readings  give,  for  the  index  error  e  of  the  declination-circle, 

First  mark,  2e=    —19' 

Second  mark,  2  e=  —  15' 

Third  mark,  2  e=  — 14' 

M'ean,  e—  —   8' 

The  following  readings  of  the  declination-circle,  when  the  telescope  was  pointed  on  the  center  of  the 
sun,  were  made  to  determine  the  error  in  the  direction  of  the  polar  axis  of  the  instrument : 


Chronometer 

Sun's  hour- 

Readings  of  Verniers. 

Resulting  distance 

Pole  of  instrument 

times. 

angle. 

of  pole  of  instru- 

beyond  pole   of 

I. 

II. 

ment  from  sun. 

the  earth. 

h.     m. 

h.    m. 

o               r 

0                     / 

December  21 

22     24 

i     57 

336        15 

157       4 

E. 

113     28 

+                          2 

23     16 

I        4 

336            5: 

156     57 

E. 

"3     37 

+                        H 

December  22 

I         0 

+       o     39 

335     52 

iSf>     44 

E. 

"3     50 

-H                   24 

I       5 

+       o    44 

203     30 

24     23 

W. 

"3     49 

+                   23 

3       2 

+         2      41 

335     47 

156     41 

E. 

"3     54 

+                 28 

From  these  five  observations  it  is  concluded  that  the  pole  01  the  instrument  was  directed  to  a  point  18' 
below  and  25'  east  rrom  the  pole  of  the  heavens. 

Rigorously  the  preceding  observations  suffice  for  the  complete  determination  of  the  angle  which  the  line 
of  motion  of  the  instrument  in  declination  makes  with  the  meridian  at  any  point.  But,  to  have  a  check  on 
the  correctness  of  the  results,  several  transits  of  pairs  of  stars,  near  in  R.  A.  but  more  distant  in  declination, 
were  observed  over  the  middle  wire  of  the  telescope,  the  pointing  of  the  latter  in  R.  A.  remaining  unchanged 


REPORT  OF  PROFESSOR  NEWCOMB. 


between  the  transits  01  each  pair.     These  observations  were  made  on  the  night  preceding  the  eclipse,  and 
are  as  follows : 


Transit  of  ft  Ceti  over  middle  wire  .• 

Transit  of  e  Piscium,  telescope  being  moved  in  declination  only 


Difference  of  mean  times  of  transit 

Difference  of  sidereal  times  of  transit  .... 
Difference  of  right  ascensions  of  stars  .... 
Amount  by  which  the  southern  star  passes  too  late 


Transit  of  y  Geminorum  . 
Transit  of  Sirius     .... 
Difference  of  right  ascensions 
Southern  star  too  late 


Chronometer. 
h.     m.     '     s. 

7  41      31 

8  o     19.5 

18  48.5 

'S     Si-5 

19  8.4 

16.9 

9     18.5 
19       6.0 

9     I2-4 
36.6 


10 

IO 


Transit  of  a  Andromedae 
Transit  of  f  Pegasi     . 
Difference  of  right  ascensions 
Southern  star  too  early 


10 
10 


27     42-5 
32     14.0 

4     52-3 
20. o 


Transit  of  a  Andromedae 
Transit  of  f  Pegasi    . 
Southern  star  too  early     . 


10 
10 


35     *7 
39     47 
2I-5 


D. 


Observations  with  Sextant  for  Latititil/-. 

DECEMBER  15,  1870. — Double  altitudes  of  the  sun's  limbs  observed  at  the  telegraph  office.     Index  cor- 
rection of  sextant,  +  20".     Temperature  65°.     Chronometer  time  of  apparent  noon,  o*"  17™  36". 


Chronometer. 

Limb. 

Reading  of 
sextant  for 
double  alt. 

Resulting 
mer.  alt.  of 
center. 

Result. 

h.    m.     s. 

o          ,          n 

0                1 

c        ,          ,, 

o    22     30 

L. 

60     37       o 

30    33     56 

Mean  observed  meridian  altitude.  .    3034     4 

L 

60     35     40 

10    11     t;v 

u 

61     40     25 

•5Q         1J.            8 

Altitude  of  equator  53  51  35 

u 

6  1     10     10 

•an      1J.       12 

Latitude.    ...                                     36     8  25 

u 

61     18     *o 

1O      "34.       I  Q 

Reduction  to  station   —     i  28 

60     31     30 

1O      11       t(O 

Latitude  of  station  .    .                            36     6  57 

Double  altitudes  of  Polaris.     Index  correction,  +  30".     Temperature,  57°. 


Chronometer. 

Limb. 

Reading  of 
sextant  for 
double  alt. 

Resulting 
mer.  alt.  of 
center.    • 

Result. 

h.     m.      s. 
10     10    30 

74  35  30 

«           /         II 

h.  m.    s. 
Sid.  time  of  mean  of  observations   .      3310 

Latitude.           .                                     36    8  25 

Latitude  of  station  36     657 

10     19    20 

74  3i  30 

.     .     . 

3— E 


i8 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


DECEMBER  20. — Double  altitudes  of  sun  observed  at  Buena  Vista,  (eclipse  station.)  Index  correction, 
+  18".  Chronometer  time  of  apparent  noon,  o'1  20"'  12".  Refraction,  i'  41"  for  upper,  and  i' 44"  for 
lower  limb. 


Chronometer. 

Limb. 

Reading  of 
sextant  for 
double  alt. 

Resulting 
mer.  alt.  of 
center. 

Result. 

h.    m.     s. 

o           ;          ii 

0                 1                   ,, 

o         ;       it 

o    24     53 
o    26     25 

U. 
U. 

61     27     10 
6  1     26    20 

30      26      22 
1O      26      2^ 

Mean  observed  meridian  altitude.  .   30  26  21 

o     27    40 

U. 

61     25     15 

30      26      22 

Altitude  of  equator  ^3  53  16 

o     28     45 

L. 

60     19      o 

30      26      19 

Latitude  of  station  36     6  44 

o    29     37 

L. 

60     1  8     10 

30    26     16 

o    30    37 

L. 

60     17     10 

JO      26      22 

DECEMBER  26. — Double  altitudes  of  a  Ceti  and  Polaris  observed  at  the  house  of  the  American  consul. 
Index  correction,  +  43".     Correction  chronometer  for  local  mean  time,  — 22'"  23". 

a  Ceti. 


Chronometer. 

Reading  of 
sextant  for 
double  alt. 

Resulting 
latitude. 

• 

h.     m.    s. 

7       5     20 

69     40     35 

0                  1             It 

36      7     52 

Mean  latitude     36     7     41 

7      8     25 
7     10     28 

69     30     15 
69     23     15 

36      7     55 
36       7     37 

Reduction  to  station      i       8 

7     12      8 

69     16    45 

36      7    35 

7     13    35 

7     iS     50 
7    27      5 
7    29      5 

69     it     10 

75      2     15: 
75      2    45 
75      2     50 

36      7    27 
3<J       7     43 

Polaris. 

0              1             '1 

Mean  lat.,  giving  half  wt.  to  first  obs.    36     8     12 

7     30    4° 

75       2     30 

r  36      3     15 

7     33      o 
7     3f>     50 

75       3     10 
75      3      o 

Latitude  of  station  36     7       4 

Summary  of  Results  for  Latitude  of  Station. 


INDIVIDUAL  RESULTS. 


December  15.  Sun, 
December  15.  Polaris, 
December  20.  Sun, 
December  26.  a  Ceti, 
December  26.  Polaris, 


36     6    57 

December  15. 

36     6     57 

December  20. 

36     6     44 

December  26. 

36     6     33 

Mean, 

36     7       4 

MEAN  BY  DATES. 


36  6  57  with  weight  3 
44  with  weight  i 
49  with  weight  4 

36     6     51  ±  4 


REPORT  OF  PROFESSOR  NEWCOMB. 


Sextant  Observations  for  Cinrcction  <>f  Chronometer. 


Date  and 
station. 

Object. 

Limb. 

Chronometer 
time. 

Sextant 

reading  for 
double  alt. 

Geocentric 
altitude  of 
center. 

Correction 
of  chronom. 

Remarks. 

h.      in.     s. 

0                   .                   II 

. 

in.       s. 

Dec.  14.9, 

Sun    . 

U. 

23     10     43 

57     37     20 

28     30     54 

—    22        6 

Observations  very   uncertain, 

Telegraph 

U. 

23     14     25 

58       2     45 

28     43     37 

13 

owing  to  bad  definition  of  the 

Office. 

L. 

23     15     25 

57       5     20 

28     47     29 

5 

sun's  limb  in  the  haze. 

L. 

23     17     30 

57     18     30 

28     54       4 

IO 

Mean  correction,  —  22m8'.5. 

Dec.     15, 

Sun    . 

U. 

3     5&       9 

23     19      o 

ii     19     10 

-    22      16.3 

Temperature,  68°  ;  index,  +40". 

Telegraph 

U. 

3     57     29.5 

22     54     15 

II       6     45 

16.3 

Mean  correction,  —  22m  i6'.3. 

Office. 

U. 

.3     53     30.5 

22     35     50 

10     57     27 

16.3 

U. 

3     59     3S 

22       15       IO 

10     47       I 

17.3 

U. 

4       o     34 

21     57     35 

10     38       9 

16.3 

U. 

4       5     13 

20      31       20 

9     54     45 

18.8 

L. 

4      10       2 

17     54     I0 

983 

13.0 

a  L)-rse    . 

6     19     30 

6>    45       o 

3r     51     M 

—    22       l8.0 

Temperature,  60°  ;  index,  +30". 

6     24     10 

62       3     20 

31        O      22 

14.8 

Mean  correction,  —  22mi6'.i, 

6     26     24 

61     15     55 

30      36      36 

16.1 

6     29     15 

60     14     50 

30       6       2 

15.6 

Jupiter    .' 

. 

9     54     37 

117      7     30 

58     33     25 

-    22      16.4 

Temperature,  57°. 

9     58     54 

118     46     45 

59     23       4 

I6.I 

Mean  correction,  —  22mi6a.g. 

10       o     25 

119     21     15 

59     40     18 

19.4 

10      i     45 

119     53     10 

59     56     16 

15-6 

10        2      56 

120     19     45 

60       9     35 

16.8 

10       4       4 

120      46       15 

60      22      48 

17.0 

10       5     12 

I2r       12       IO 

60     35     50 

17.2 

a  Androm. 

. 

10     29     54 

85   .34     50 

42     46     38 

—    22      I6.O 

Mean  correction,  —  22'"i6a.8. 

10     3:     51 

84    48     30 

42     28     28 

I7.6 

Dec.     16, 

a  Lyrae    . 

. 

7     54       9-5 

30      o    20 

14     56     50 

-    22      14.2 

Temperature,  57°  ;  index,  +25". 

Telegraph 

7     56     44 

29     10     50 

14     31     59 

14.0 

Mean  correction,  —  22m  14'.  6. 

Office. 

7     59     50 

28     n     35 

14-       2     14 

14.4 

8       I     39-5 

27     37       o 

13     44     52 

I4.8 

S       4     36 

-(>     41     25 

13     i  6     57 

15.7, 

Dec.    20, 

Sun    . 

U. 

3     50     59 

25     28     10 

12      23      56 

-    22      lg.8 

Temperature,  59°  ;  index,  +18". 

Eclipse 

U. 

3-     56     58 

23     39     25 

II      29      15 

lg.2 

Mean  correction,  —22'"  19*.  i. 

Station. 

U. 

3     59     25.5 

22     54       5 

ii       6     27 

I8.3 

F. — Observations  for  Index  Correction  of  Sextant. 

Each  result  is  generally  the  mean  of  two  observations. 


Readings 

"Off"  arc. 

"On"  arc. 

d.     h. 

«      "i        „ 

, 

i, 

December  14,   23 

Sun    .    . 

359     27       o 

o    32     50 

+             5 

15.      i 

Sun    .    . 

359     26       5 

o     33     15    +           20 

4 

Tower*. 

359    47    25 

o     lo    42 

+           40 

ii 

Jupiter  . 

359     59      5 

359     55     55 

+           30 

2O         0 

Sun    .    . 

359     27     12 

o    32     12 

+           18 

26      7 

Moon    . 

359    27     58 

o    30    37 

+           42 

"  Measures  of  the  width  of  the  signal  tower,  about  4,000  feet  distant.    Correction  for  parallax  — 16" 


20 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


G. —  Transits  observed  with  the  Transit  Instrument  at  the  Kctipse 


Number. 

Date. 

Object. 

IM 

O 

«    S 
.2   1 

•S  "3 

o 

CU 

Seconds  of  transit  over  wires. 

Resulting  time 
of  transit  over 
middle  wire. 

Level  em- 
ployed. 

j 

Level  in- 
dication. 

I. 

2. 

3- 

4- 

5- 

6. 

7- 

1870. 

s. 

s. 

s. 

s. 

s. 

s. 

s. 

h.    m.        s. 

d. 

I 

2 

3 
4 
5 
6 

7 

Dec.    20 

Polaris      .... 
o  Piscium    .... 

w. 
w. 

16  8 

30.0 

3-0 
29.5 

9-5 

I.O 

50.5 

22.0 
14-5 

50.7 

21.7 
44.0 
43-7 
35-5 

ii.  3 

42-5 
36.5 
5-0 
57-3 

7     37     30.0 
S       4       7.6 

8     17     59-9 
8     31     39-2 
8     43     55-6 
9       2       1.4 
9     20     53.4 

A 
A 
A 
A 
A 

2.6  E. 
3-0  E. 
8.6  E. 
10.4  E. 
6.oE. 
8.5  E. 
8.0  E. 

50  Cassiopere      . 
fi  Cell     

w. 

w. 

52.1 

1.0 

39.5 

55-5 

w. 

2.3 

y  Ceti 

E 

a  Ceti      

E. 

50.0 

10.5 

31-8 

53-7 

8 

a  Persei                    , 

E. 

46.0 

9.0 

5L3 

24-5 

56.3 

28.5 

2.0 

9     4°     24.4 

3.0  W. 

9 

21 

ji  Arietis      .      .      ,      . 

57-7 

.  , 

,  . 

.      . 

27-5 

.      . 

13.0 

8       9       5.2 

. 

2.5E. 

10 

a  Arietis      .... 

.  . 

40.7 

4.0 

27.8 

5O.O 

13-0 

36.3 

8     21     27.4 

A 

6.1  E. 

ii 

12 
13 

M 
15 
I& 

17 

22 

i  Cassiopese 
5  UrsaeMinoris,  S.  P.  .  • 

18.5 

II.  3 

7-0 

59-7 
26.0 

53-7 
55-3 
35-8 

37-7 
38.0 

47-7 

21.  0 
56.3 
57-5 
9-3 
II.  0 
20.3 

8     40       6.8 
8     48     55.0 

9     if>     53-3 
9     28     50.2 
9     3&     32-2 
9     32     33-4 
9     57     10.8 

B 

A 

2.9  E. 
4-7  W. 
4-3  W. 

4.2\V. 
7.9  E. 

I8.2W. 
(..4  W. 

a  Ceti      

W. 

50.5 

C  Arietis      .... 
n  Persei        .... 

W. 
W. 

42.0 

28.3 

'3-5 

5-5 

n  Persei       .... 

E. 

)/  Tauri  ..... 

E. 

47-5 

10.5 

33-5 

18 

*9 
20 

7  Eridani      .... 
j  Tauri  

E. 
W. 

t3.5 

34.5 

56.3 

18.7 
40.5 
42.8 

39-7 
3-0 

5-2 

1-7 
24.7 
27.0 

23.8 
46.3 

48.6 

10      9     18.5 
10    29    40.6 
10    45     42.6 

A 
A 
A 

4.1  W. 
i8.5W. 
4.2\V. 

a.  Tauri   

W. 

.      . 

58.3 

21.  0 

21 

t  Aurigte     .... 

W. 

30.5 

55-5 

21.2 

46.0 

n.  8 

37.o 

1.2 

n       5     46  .  o 

A 

9.4  W. 

22 

e  Ursse  Minoris,  S,  P.  . 

W. 

.  . 

.    . 

41.0 

ii     15     41.0 

A 

2.5W. 

23 

23 

o  Lyre    

w. 

8.5 

36.2 

2-5 

28.8 

56.6 

23-4 

49.6 

o    47     29.1 

A 

10.8  E. 

NOTES. 

I.  The  two  wires  are  discordant  by  30",  and  the  observation  is  not  used. 

9.  Before  this  observation  the  transit  wires  were  found  far  from  vertical,  though  they  had  been  carefully  adjusted  on 
the  I7th.  They  were  readjusted,  and,  on  examining  the  collimation  by  reversal  on  a  distant  object,  the  middle  wire 
was  found  too  near  the  clamp  side  of  the  instrument  by  an  amount  estimated  at  o".io  or  oB.i2. 

8,19.  Before  each  of  these  observations  the  azimuth  was  accidentally  changed  by  moving  the  azimuth-screw. 


REPORT  OF  PROFESSOR  NEWCOMB. 


21 


Station  to  determine  the  error  of  the  Chronometer  an  Local  Time. 


Number. 

Correction  for  — 

Minutes    and 
seconds  of 
transit  over  a 
vertical  circle. 

Computed  mean 
time  of  transit 
over   meridian. 

Difference. 

Coefficient 
of  azimuth. 

Adopted 
azimuth. 

Correction  of 
chronometer. 

Collimation. 

Level. 

s. 

s. 

m.        s. 

h.    m.'      s. 

m.        s. 

s. 

m.       s. 

I 

o.oo 

4.0 

37     26.0 

7     15     12.0 

22     14.0 

—       32.6 

-t-     0.50 

-  22     30  : 

2 

0.00 

—            O.I 

4       7-5 

7     41     46-9 

20.  6 

+•         0.47 

20.4 

3 

o.oo 

-         i.5 

17     58.4 

7     55     38.7 

19.7 

-         1.8 

20.  6 

4 

0.00 

-         0.6 

31     38.6 

8       9     17.2 

21.4 

+        0.47 

•     • 

21.2 

5 

o.oo 

-        0.9 

43     54-7 

8     21     34.3                      20.4 

-         1.3 

21.  0 

6 

o.oo 

-        0.5 

2       o.g 

8     39     39.6                      21.3 

+        0.55 

. 

21.  0 

7 

o.oo 

-         o-5 

20     52.9 

8     58     31.8     '                 21.  I 

+        0.55 

. 

20.8 

8 

o.oo 

+         0.3 

40     24.7 

9     18       4.0                      20.7 

-        0.35 

. 

20.9 

9 

—       0.32 

0.17 

9       4-7 

7     46     45-5     i                 19.2 

+        0.29 

-     5-0° 

20.7 

10 

—       0.32 

—         0.42 

21       26.7 

.7     59       6-8 

19.9 

4-        0-25 

. 

21.  1 

ii 

-      0.5 

0.4 

40         5-9 

8     17     38.3 

27.6 

—         1.30 

. 

21.  I 

12 

+           1.2 

-        o-5 

48     55.7            8     26     54.2 

i.5 

4-         3-9° 

. 

21.0 

13 

+       0.30 

+        0.23 

i&     53-9            8     54     35.9 

iS.o 

+        0.55 

6.30 

21.5 

14 

+       0.32 

+        0.28 

28     50.8           9      6     31.1                     T9-7 

+        0.29 

. 

21.5 

15 

+         0.45 

0.79 

36     31.8 

9     14       8.1                      23.7 

—        0.36 

. 

21.4 

16 

o-45 

+         i-55 

32     34-5 

9  •  IO      T2.2                             22.3 

—        0.36 

—     2.90 

31.3 

17 

—        0.32 

+         ".-15 

57     ii.  o           9     34     49-7                      21.3 

+        0.24 

22.0 

18 

0.31 

+         o.iS 

9     18.4            9     46     59.5                      18.9 

+  _      0.79 

21.2 

IQ 

+        0.32 

+         1.41 

29     42.3 

10       7     22.6 

19.7 

+        0.36 

•     6.30 

22.0 

20 

+        0.32 

+•         o-3° 

45     43.2 

10     23     24.0 

19.2 

+        0.35 

21.4 

21 

+        0.36 

+         0.75 

5     47-1 

10     43     25.2 

21.9 

4-         0.06 

. 

22.3 

22 

—            2.2 

-         0.6 

15     38.2 

10     53     56.5 

21       41.7 

+         6.50 

22.6 

23 

+         0-39 

—         0.87 

47     28.6 

o     25       6.2 

22       22.4 

—         0.05 

•     • 

22.7 

NOTES. 

22.  On  the  following  morning  the  collimation  was  examined  by  reversal,  and  the  middle  wire  found  too  near  the1 
clamp  end  of  the  axis  by  or.O3t  of  the  azimuth-screw.  The  observation  was  made  in  sunshine.  The  results  for  chro' 
nometer  error  seem  to  show  that  this  collimation  is  fictitious;  but,  as  the  error  will  be  eliminated  from  the  mean  of 
observations  made  in  both  positions  of  the  instrument,  I  have  made  no  change  in  the  result. 


22 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


H. 
Determination  of  Constants  pertaining  to  the  Transit-Instrument. 

Calling  wire  I  that  nearest  the  clamp  end  of  the  axis,  the  eight  transits  observed  over  both  wires,  I  and 
IV,  were  taken,  and  the  observed  intervals  separately  reduced  to  the  equator  by  multiplying  them  by  cos  <J. 
The  same  thing  was  done  with  the  ten  transits  observed  over  wires  IV  and  VII.  The  results  were: 

VII  —  IV=   63.28 

IV-      1=   63.34 

VII-     1=126.62 

The  intermediate  wires  were  determined  by  means  ot  the  azimuth-screw  of  the  instrument.  The  latter 
being  pointed  on  a  distant  mark,  the  readings  of  the  screw  for  coincidence  of  the  several  wires  with  the  mark 
were  as  follows : 


Wires. 

Microm. 

i 

Intervals. 

Intervals 
in  time. 

Reduction  of 
each  wire 
to  IV. 

r. 

r. 

s. 

s. 

I. 

20.806 

1.620 

21.56 

+         f'3-54 

II. 

19.186 

1.590 

2J.I7 

+         41-98 

III. 

17.596 

1.563 

20.81 

+         20.81 

IV. 

16.033 

1.627 

21.67 

o.oo 

V. 

14.406 

1.584 

21.09 

21.67 

VI. 

12.822 

1.528 

20.34 

42.76 

VII. 

11.294 

63.10 

From  the  first  and  last  of  these  readings  is  concluded  : 

VII  —  I  —  g'.s  1 2  =  1 269.62 


and  the  intervals  and  reductions  to  middle  wire  are  thence  deduced. 

To  find  the  value  of  one  revolution  of  the  level-screw,  the  instrument  was  fastened  in  its  Y's  by  an 
elastic  cord,  and  the  stand  was  then  tipped  over  so  that  the  level-screw  was  horizontal.  The  following  three 
intervals  were  then  determined  in  the  same  way  with  that  employed  in  investigating  the  azimuth  screw : 

II —  I  =  ir.59o;  difference  from  azimuth  screw = — 0^030 
III —  II=iT.569;  difference  from  azimuth  screw  =  — or.o2i 
IV — III  =  ir.52i ;  difference  from  azimuth  screw= — or.o42 


From  this  is  concluded, 


REPORT  OF  PROFESSOR  NEWCOMB.  23 

The  Spirit- Levels. 

These  were  put  upon  the  axis  of  the  instrument  in  succession,  and  their  bubbles  were  read  in  different 
positions  of  the  level-screw,  as  follows  : 


Level  B. 

Level  A. 

T         . 

T        . 

W. 

E. 

W. 

E. 

r. 

d. 

d. 

r. 

A 

d. 

.109 

28.0 

77.0 

.235 

55-5 

82.0 

.210 

45-5 

58.5 

-350 

79.0 

57.8 

.300 

60.0 

43-0 

.250 

56.0 

80.0 

.100 

20.  o 

33-5 

-370 

81.5 

55-o 

.300 

57-o 

45-5 

.240 

51-5 

84.0 

.400 

74-0 

28.0 

.400 

85.5 

49.5 

.100 

15.0 

88.0 

Having  regard  to  the  value  just  found  for  one  revolution  of  the  level-screw,  it  is  concluded  that 

One  division  of  level  A  =  o8.o65 
One  division  of  level  B  =  o8.o72 

I, 

Exchange  of  Signals  with  Professor  Hall  at  Malta,  through  the  Palmoiith,  Gibraltar  and  Malta  Cable. 

DECEMBER  15. 

A  signal  was  sent  every  fifteen  seconds  from  4h  45'"  o8  to  4h  50'"  o8,  chronometer  time,  but  the  signal 
which  should  have  been  sent  at  4h  49™  45"  was  half  a  second  late. 
Signals  from  Malta  were  received  at  the  following  times  : 


S3 


54 


S. 

h.       m. 

s. 

47.1 

4    55 

2.2 

2.4 

17-3 

17.4 

32.4 

32.4 

47-3 

47-3 

56 

2-5 

2-5 

'7-3 

!7-3 

32.2 

32-3 

47-4 

47-3 

57 

2.4 

17.4 

Next  morning,  December  16,  civil  time,  signals  were  sent  to  Malta  every  fifteen  seconds  from  23'"  32™  o8 
to  23''  37m  os. 


24  OBSERVATIONS  OF   THE  ECLIPSE  OF  DECEMBER  22,  1870. 

Signals  from  Malta  were  received  as  follows  : 

h.     m.         s. 

23     39     l8-7  = 

48.0: 

40  3.0 
17.9: 

48.1 

41  3.2 
18.2 

33-2 
48.1 

NOTE. — The  signals  were  sent  by  pressing  a  key  simultaneously  with  the  proper  beat  of  the  chronometer.  They  were 
received  by  having  an  operator  strike  a  key  as  soon  as  he  saw  the  motion  of  the  image  reflected  from  the  mirror  of  the  galvanom- 
eter. The  time  of  this  stroke  was  noted  by  the  observer  at  the  chrpnometer. 


h. 

m.           s. 

23 

42       3-2 
18.0 

33-° 
48.1 

43       3-2 
18.3 

33-2 
48.1 

44       3-° 
18.3 

REPORT 


OF 


PROFESSOR  ASAPH   HALL,  U.  S.  N. 


4— E 


REPORT    OF    PROFESSOR    HALL,    U.S.   N. 


UNITED  STATES  NAVAL  OBSERVATORY,  Washington,  February  27,  1871. 

SIR  :  I  have  the  honor  to  submit  the  following  report  of  my  observations  of  the  solar  eclipse  of 
December  22,  1870. 

I  left  New  York  November  2,  on  the  Cunard  steamship  China,  and,  arriving  at  Liverpool  November 
13,  proceeded  thence  by  the  way  of  London  to  Southampton,  and  from  that  port  by  the  steamship  Poonah, 
of  the  Peninsular  and  Oriental  Line,  to  Malta,  and  from  Malta  by  the  Florio  steamer  to  Syracuse ;  arriving 
at  Syracuse  December  8.'  I  returned  to  Malta  December  12,  and  remained  there  four  days  for  the  purpose 
of  exchanging  telegraphic  signals  for  longitude  with  Professor  Newcomb  at  Gibraltar,  and  with  Professor 
Harkness  at  Syracuse. 

We  left  Syracuse  the  day  after  the  eclipse,  and,  passing  through  Italy  and  Central  Europe,  I  returned 
to  England  by  the  way  of  Ostend  and  Dover.  Leaving  Liverpool  January  21,  I  arrived  at  Washington 
February  3,  1871. 

I  wish  to  express  my  sincere  thanks  to  Signer  Nunzio  Stella,  the  American  consular  agent,  and  to  the 
civil  and  military  authorities  of  Syracuse,  for  their  kind  attentions  to  our  party,  and  for  the  facilities  afforded 
us.  I  am  indebted  also  to  Signor  Bisani,  the  English  consular  agent,  for  his  assistance. 

At  Malta  I  was  under  great  obligations  to  Mr.  Lyell  T.  Adams,  our  consul,  and  to  Mr.  B.  Smith  and 
Mr.  Edward  Rosenbusch,  superintendents  of  the  telegraph  offices  in  Malta.  It  was  only  through  the  energy 
and  skill  of  Mr.  Rosenbusch  that  we  were  able  to  make  the  telegraphic  connections  between  Malta  and 
Syracuse.  I  have  to  offer  my  thanks  to  Messrs.  Pisani,  Portelli,  Fauqueir,  and  other  gentlemen  connected 
with  the  telegraph  offices,  for  the  assistance  rendered  me  in  exchanging  the  signals.  To  Mr.  Pisani  I  am 
also  indebted  for  assistance  in  my  time  observations.  I  am  under  special  obligations  to  Captain  G.  L. 
Tupman,  of  the  Royal  Marine  Artillery,  who  assisted  me  in  many  of  my  sextant  observations,  and  who  fur- 
nished me  with  much  local  information.  M.  Berthet,  optician  at  Valetta,  very  kindly  allowed  me  the  use 
of  his  fine  transit-instrument.  The  whole  party  is  much  indebted  to  the  Messrs.  Negus,  of  New  York,  who 
furnished  us  with  excellent  chronometers. 

THE    ECLIPSE. 

My  observing  station  in  Syracuse  was  on  the  "  Bastione  San  Filippo,"  a  little  north  of  the  gate  "  Prima 
Porta  Terra."  My  telescope  was  a  comet-seeker  by  Ploessl,  with  a  3^-inch  object-glass  and  a  magnifying 
power  of  about  fifty.  The  following  are  my  observations  of  the  times  of  contact  and  the  bisections  of  solar 
spots.  The  times  observed  are  those  of  the  chronometer  Negus  1228,  and  were  observed  with  a  dark 
glass  at  the  eye-piece  except  those  of  the  second  and  third  contacts,  or  the  beginning  and  end  of  total 
eclipse,  which  were  observed  without  the  shade : 


Object. 

Ch.  Negus  1228. 

Chron.  corr. 

Local  M.  T. 

Notes. 

First  contact    .    .    . 
Spot  d  

h.     m.        s. 

n     37     35-0 
n     43     16  o 

h.   m.       s. 
H-io     38.0 

I       O      38    O 

h.    m.       s. 
o     38     13.0 

Fair. 

Spot/  

I       O      38    O 

Spot  h  

Spot  m 

Spot  n  

O      1J.      46   O 

I       O      38    O 

Spot  o\  

O      17       17    O 

I       O      38    O 

Spot  ^2  

I      O      38    O 

Second  contact   .    . 
Third  contact  .    .    . 
Fourth  contact    ,    . 

I          2       17.5 

i       4       o.o 

2       21       20.5 

i     o    38.0 
i     o    38.0 
-H     I     o     38.0 

2        2      55.5 

2      4     38.0 
3     21     58.5 

Good. 
Poor. 
Fair. 

28 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


The  annexed  diagram  of  the  solar  spots  was  made  about  an  hour  before  the  beginning  of  the 
will  serve  to  identify  the  spots  observed.  The  observed 
times  of  contact  agree  very  closely  with  those  computed 
from  the  data  of  the  American  Ephemeris,  the  longitude 
of  Syracuse  being  assumed  as  —  6h  9™  2$*.6;  but  as  our 
attempt  to  determine  the  longitude  of  Syracuse  from 
Greenwich  was  unsuccessful,  on  account  of  a  break  in  the 
submarine  cable  between  Gibraltar  and  England,  no 
accurate  comparison  with  the  tables  can  be  made.  Assum- 
ing, however,  that  the  longitude  of  Gibraltar  is  tolerably 
well  known,  our  telegraphic  connection  with  that  point 
enables  us  to  determine  the  longitude  of  our  observing 
station  at  Syracuse.  In  this  way  Professor  Harkness 
finds  for  the  longitude  east  of  Washington 

Cli  gin   2jS  g 

By  combining  the  results  of  all  the  sextant  observa- 
tions, Professor  Harkness  has  deduced  as  the  most  probable 
value  of  the  latitude  of  our  station 


eclipse,  and 


I  have  adopted  therefore 


?=+37°3'53" 
-i  = — 6h  g111  27".8 


and  a  computation  from  the  data  of  the  American  Ephemeris  gives  the  following  times  of  contact : 


Phase. 

Computed  times. 

Observed  times. 

A/. 

h.    m.       s. 

h.    m.       s. 

s. 

First  contact    .    .    . 

o     38     19.2 

o    38     13.0 

-*-       6.2 

Second  contact   .    . 

2       3       5-1 

2         2       55.5 

+    9.6 

Third  contact  .    .    . 

2       4     46.1 

2       4     38.0- 

+     8.1 

Fourth  contact    .    . 

3       22         S.O 

3     21     58.5 

+     9-5 

The  following  differential  equations  will  serve  for  computing  changes  in  the  times  of  contact  produced 
by  small  changes  in  the  position  of  the  observing  station : 

dt=  —  o.oi4</<p — 1.525  <#,  first  contact, 
dt=  —  0.014  dtp —  1.509^,  second  contact, 
•    dt=  —  o.oi^dy — 1.423^,  third  contact, 
dt=  —  o.oi4</yi — 1.300^,  fourth  contact, 

dtp  being  expressed  in  seconds  of  arc,  and  d\  in  seconds  of  time.  The  value  of  y  is  supposed  to  increase 
positively  toward  the  north  and  that  of  X  toward  the  west. 

The  times  of  contact  computed  by  Signer  Agnello,  of  the  Palermo  Obervatory,  are  on  an  average 
25  seconds  earlier  than  those  which  I  have  computed,  except  the  time  of  first  contact,  which  is  88  seconds 
later,  evidently,  a  misprint  or  the  result  of  some  error  of  computation.  Signor  Agnello's  data  is  that  of  the 
English  Nautical  Almanac. 

My  chief  purpose  during  the  total  eclipse  was  to  observe  the  structure  of  the  corona,  with  special 
reference  to  the  curved  and  radiating  lines  seen  in  previous  eclipses,  but  the  condition  of  the  sky"  was  such 
that  this  observation  was  unsatisfactory.  During  the  last  quarter  of  an  hour  of  the  first  partial  phase  it 
appeared  hopeless  that  the  total  eclipse  would  be  visible,  the  sun  being  covered  by  a  thick  cloud.  This 
cloud,  however,  had  a  slow  motion  upward  and  toward  the  east,  and  a  few  minutes  before  totality  the  nar- 


REPORT  OF  PROFESSOR  HALL.  2Q 

row  crescent  of  the  sun  appeared  through  the  clouds.  On  account  of  these  clouds  1  was  able  to  take  off 
my  colored  glass  shade  and  watch  the  disappearance  of  the  sun  without  any  protection  or  inconvenience  to 
the  eye.  The  apparent  diameters  of  the  sun  and  moon  being  nearly  equal,  the  bright  crescent  became 
extremely  long  and  narrow,  and  broke  up  into  bits  and  fragments,  but  I  noticed  no  color  nor  anything 
remarkable  before  the  disappearance  of  the  last  long,  thin  remnant.  After  recording  my  observed  time  of 
the  beginning  of  total  eclipse  I  pointed  the  telescope  to  the  east  limb  of  the  moon  and  swept  around  toward 
the  south  back  to  the  starting  point.  I  should  not  estimate  the  extent  of  the  corona  to  be  more  than  five 
or  ten  minutes  from  the  limb  of  the  moon,  but  the  clouds  make  this  estimate  quite  uncertain ;  and  with 
regard  to  the  form  or  outline  of  the  corona  it  could  not,  I  think,  be  observed  with  accuracy.  The  appear- 
ance of  the  corona  in  the  telescope  was  that  of  a  soft,  white,  diffused  light.  There  was  very  little  appear- 
ance of  the  radiating  lines  shown  in  many  pictures,  and  I  saw  no  curved  streamers.  Near  the  southwestern 
point  of  the  moon  there  was  apparently  a  deep  opening  in  the  corona,  reaching  nearly  to  the  limb  of  the 
moon,  but  on  account  of  the  clouds  this  opening  was  very  indistinct. 

After  sweeping  around  the  moon  I  pointed  the  telescope  on  one  of  the  large  protuberances  near  the 
eastern  limb  of  the  moon,  but  could  see  nothing  of  the  spotted  or  cellular  appearance  seen  by  Professor 
William  A.  Rogers  in  the  eclipse  of  August  7,  1869.  The  protuberances,  which  were  very  numerous,  were 
uniformly  of  a  dull  pink  color.  Then  having  some  fifteen  or  twenty  seconds  to  spare,  I  looked  at  the 
eclipse  with  the  naked  eye.  The  moon  was  still  covered  with  the  light  and  shifting  clouds,  but  as  they 
were  rising  and  passing  toward  the  east  the  lower  and  southwestern  part  of  the  moon  was  much  the  clearer. 
At  this  point  the  corona  was  quite  bright,  and  here  several  delicate  streamers  shot  down  to  the  distance  of 
eight  or  ten  degrees.  There  was  no  color,  and  to  the  naked  eye  the  corona  appeared,  as  in  the  telescope,  of 
a  soft,  white  light.  Putting  my  eye  back  to  the  telescope  I  observed  the  first  reappearance  of  the  sun 
through  a  deep  notch  in  the  moon's  limb.  This  a  little  disturbed  me  and  made  my  observation  of  the  end 
of  totality  somewhat  uncertain. 

The  darkness  during  total  eclipse  was  much  less  than  during  the  eclipse  of  August,  1869.  As  the 
totality  approached  it  became  quite  cold,  and  a  strong  wind  arose,  but  as  my  telescope  had  a  solid,  firm 
mounting,  the  wind  gave  me  no  trouble.  I  did  not  see  the  planet  Saturn,  which  was  a  little  north  of  the 
moon,  but  my  attention  was  not  specially  directed  to  the  discovery  of  the  planet. 

The  general  appearance  of  the  total  eclipse  was  something  as  follows :  The  black  moon  in  the  center 
surrounded  with  a  narrow  rim  of  bright  light  a  quarter  or  half  a  minute  in  thickness.  Above  this  rim  rose 
the  dull  pink -colored  protuberances,  and  beyond  these  extended  the  white  corona,  the  whole  making  a  very 
beautiful  sight.  I  refrain  from  attempting  to  make  any  picture  of  the  eclipse.  On  account  of  the  sudden- 
ness, the  beauty  and  grandeur  of  the  phenomena  displayed,  it  is  very  difficult  to  make  a  correct  picture  by 
hand-sketching ;  and  so  much  must  the  memory  be  relied  on,  and  so  great  is  the  opportunity  for  the  play 
of  the  imagination,  that  I  can  have  but  little  faith  in  such  pictures.  Photography  appears  to  furnish  the 
only  means  of  making  a  truthful  picture.  At  Syracuse  we  were  fortunate  in  having  the  companionship  of 
three  English  observers,  Messrs.  Brothers  and  Fryer,  of  Manchester,  and  Mr.  Griffith,  of  Harrow.  Messrs. 
Brothers  and  Fryer  obtained  several  photographs  of  the  total  eclipse,  and  one  which  was  understood  to  be 
very  satisfactory. 

At  the  instant  of  the  beginning  of  total  eclipse  I  noticed  in  the  telescope  an  appearance  that  it  may 
be  worth  while  to  describe.  The  protuberances  darted  quickly  into  view,  and  there  was  a  flashing  back  of 
the  sunlight,  and  an  apparent  mingling  of  red  and  white  light  that  was  very  striking.  The  appearance  was 
somewhat  like  that  given  by  Mr.  Oilman  in  his  picture  of  the  eclipse  of  1869,  but  it  was,  I  think,  an  optical 
illusion,  for  after  recording  my  time  and  putting  my  eye  again  to  the  telescope  the  appearance  was  entirely 
gone. 

With  regard  to  the  long  streamers  seen  near  the  end  of  totality,  I  had  the  impression  when  seeing  them 
that  they  were  not  of  the  corona  proper,  but  were  produced  in  the  earth's  atmosphere.  This  impression  was 
caused,  perhaps,  by  the  proximity  of  the  clouds,  and  by  the  resemblance  of  the  streamers  to  the  phenomenon 
commonly  spoken  of  as  the  "sun's  drawing  water,"  only  the  streamers  were  much  more  delicate  and  more 
like  what  we  see  sometimes  in  our  atmosphere  on  a  hazy  day. 


30  OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 

SEXTANT  OBSERVATIONS. 

I  give  .below  the  observations  for  time  and  latitude  made  at  Malta  and  Syracuse  with  the  Pistor  & 
Martins  patent  sextant  No.  107.  The  altitudes  were  observed  by  myself,  and  the  times  at  Malta  by  Captain 
Tupman  and  Mr.  Pisani ;  at  Syracuse  by  Professor  Eastman,  Captain  Tupman,  and  myself.  In  the  column 
of  dates  I  have  placed  the  initials  of  the  observers.  It  should  be  stated  that  the  observations  at  Malta,  until 
December  15,  were  made  with  the  low  power,  as  the  colored  shade  had  become  so  firmly  fixed  to  this  teles- 
cope during  the  transportation  of  the  instruments  that  I  did  not  succeed  in  removing  it  until  the  evening 
of  December  14. 


Date.          Chronom.  1228. 

Sextant  R. 

Corr.  chronom. 
.  and  latitude. 

Results. 

1870.               h.    m.       s.               «        '        " 

h.    m.       s. 

%          MALTA. 

Dec.     12.9          7     58     40.5            34     29       o 

+  o     57     30.0 

H.T.               7     59     37-7            34     44     3" 

29-5 

(#=+0.1250  (//;  +0.0941  </«> 

8       o     25.6            34     57     40 

30.1 

h.    m.        s.         s. 

8       i     45.2            36     23     10 

26.3 

Ac=+o     57     29.0  ±0.28 

8       3     47-5            36     56     40 

28.6 

Red.  =  +              0.6 

8       5       8.1            37     18     30 

29-3 

8       6     29.2            37     39     30 

27-5 

8       7     44.4            38       o     50 

31.0 

8         8      22.2      '         38      10      10 

30.5 

8       9     35.2            37     23     50 

28.7 

8     12     46.1           38     13     40 

29.0 

8     13     37-7            38     26     20 

26.9 

0                     1                 II 

0                   /                  It'll 

Dec.     13.0        10     58     43                61     21     30 

+  35     52     90 

f=  +  35     52     55±3-° 

H.  T.            10     59     15.5           61     22     50 

46 

10     59     49                61     22     10 

62 

ii       o     32                61     21     20 

78 

. 

ii       i     14.5           62     27     40 

31 

ii       i     49.5           62     27      o 

41 

ii       2     27.2           62     26    40                          41 

i 

ii       3     12                62     25     30 

60 

ii       3     51.5           62     25     10 

56 

ii       4     24.2            62     24     40 

56 

ii       5       o                62     24     20 

51 

ii       5     34-5 

62     23     30 

59 

ii       6       8.5            61     17     40 

66 

ii       8     10 

61     15     50 

49 

ii       8     41.2 

61      15  _  10 

50 

ii       9       7.2 

61     14     30 

5° 

h.    m.      s. 

Dec.    13.9 

7     42     48.5 

30     52       o 

+  o    57    29.8 

(#=+0.1165  i/A  +0.0825  "^ 

H.  T.  • 

7     43     21.7 

31       i     50 

31.0 

h.    in.       s.        s. 

7     43     50-6 

31       9     40 

29.2 

Ac=+o     57     28.4±o.39 

7     44     36.2 

30     17     10 

27.0 

7     45     15-3 

30     28     10 

26.4 

7     45     46.5            30     37       o 

26.0 

7     46     39-° 

30     52     10 

26.7 

7     47     25.6 

31       5     20 

26.3 

7     48     10.5 

31     i  8     40 

2S:5 

7     48     47.8 

32     34       o 

27.8 

7     49     22.2 

32     44     50 

,       31.8 

7     49     49-2 

32     52     10 

30-7 

REPORT  OF  PROFESSOR  HALL. 
Sextant  Observations — Continued. 


Date. 

Chronom.  1228. 

Sextant  R. 

Corr.  chronom. 
and  latitude. 

Results. 

1870. 
Dec.    14.0 

h.    m.      s. 

5     53     52 

6  1        9     20 

+  35     53     66 

MALTA. 
Times  by  Frodsham  watch  1915  : 

H.  P. 

5     55     12 
5     55     46 
5     5&     29 

61       8       o 
61       8     10 
62     12     10 

67 
40 

54 

h.     m.       s. 
Chr.  1228,  ii     27       o 

Fr.     1915,    6     15     28.4 

5     57       i 

62     ii     40 

49 

O.I/,, 

5     57     30 

62     ii     20 

4i 

0=  +  35     54     o±2.3     • 

5     58     23 

62       8     50 

77 

5     58     45 

62       8     50 

64 

5     59     18 

62       8     20 

55 

5     59     57 

6  1       i     40 

7° 

6       o     29 

61       i       o 

65 

6       o     56 

6100 

72 

h.    m.        s. 

Dec.    14.1 

i     43     30 

37     34     10 

+  o     57     26.1 

Jt=—  0.1222  dh  —0.0903  i/tp 

H.  P.              i     44     13 

37     22       o 

30.9 

h.    m.        s.       s. 

i     46     14 

37     50     4° 

29.4 

Af=:+o     57     28.6±o.34 

i     46     53 

37     45     5« 

27.8 

i     47     50 

37     31       ° 

26.9 

i     48     18 

37     23       o 

29.2 

i     49     37 

37      2     10 

28.5 

i     51     49 

36     43     30 

26.4 

i     53       8 

36       5     20 

29.0 

i     53     43 

35     55     40 

29.7 

i     55     56 

'  34     23     30 

26.8 

i     56     44 

34       o     40 

-    32  3 

i     57     .6 

33     55     20 

29-7 

H.  T. 

2       7     52.7 

30     54     30 

31.0 

2       8     30.3 

30     44     40 

28.0 

2       10      28.1 

31     17       o 

24-3 

2       II       2O.  O 

31       o     10 

30.9 

Dec.    14.9 

7     35     38.0 

27     26     30 

+  o     57     24.8 

flV=-t-o.  1155  dh  +0.0811  <{$ 

H.  T. 

7     36     20.5 
7     36     54.2 

27     39     40 
27     48     30 

27.0 
23.3 

h.    m.        s.         s. 
Ac=+o     57     2S.o±o.47 

7     37     54-5 

28       7     40 

28.4 

7     41     20.0 

30     13     30 

32.0 

7     42      7.2 

30      27      20 

32.6 

7     43     25.1 

30    47     50 

25.9 

7     44     35-5 

31     10      o 

32.4 

, 

7     45     44-1 

31    28    30 

28.6 

• 

7     46     15.2 

31     37     20 

28.4 

7     46     42.0 

31     45     20 

29-7 

7     47     19.8 

31     56     10 

29.9 

7     48     20.5     .       31       7     40 

27.2 

7     49       2.5 

31     18     5° 

24.6 

7     49     4°-2 

31     30      o 

26.4 

7     50     28.3 

31     43     4° 

26.9 

OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22.  1870. 
Sextant  Ob  sen  -at ions — Con  tinned. 


Date.         Chronom.  1228. 

Sextant  R. 

Corr.  chronom. 
and  latitude. 

Results. 

1870.             h.    m.        s. 

0               1                   II 

or            ii 

MALTA. 

Dec.    15.0         5     27     10 

60    45     50 

+  35     54      i 

h.     m.      s. 

H.  P.              5     27     51 

60    47     10 

14 

Chr.  1228,   ii     47       o 

5     28     44 

60    48     40 

23 

Fr.     1915,     6     35     24.0 

5     4°     21 

61       4       o 

27 

0 

6      3      6. 

61     55     10 

27 

0=+35     54     23  ±2.  7 

6     23     41 

60     52     30 

25 

6    24      9 

60     50     10 

35 

" 

6     24     45 

60    47     40 

34 

h.    m.        s. 

Dec.    15.1         i     35     30.5 

40     43     40 

+  o     57     28.1 

at=—  o.  1297  ah  —o.  1002  no 

II.  P.              i     36       1.5 

40    35      o 

31-3 

h.    m.        s.         s. 

i     36     34-5 

40    27     10 

29.6 

Ac=+o     57     2g.2±o.34 

i     37       7-0 

40    20      o 

25-3 

i     38     30.0 

38     52     40 

30.5 

1     38     53-o 

38     47      o 

29.4 

i     39     15-5 

38     42     10 

26.2 

i     39     50-5 

38     32     30 

28.9 

i     40    32.5 

38      21      2O 

30.7 

' 

i     41     23.0 

38       7     50 

32.6 

i     41     58'.  o           37     59     20 

30.6 

i     42     58.0 

37    43     50 

30.6 

1     43     44-5     ; 

38     36    40 

29.8 

I     44     25.0 

38     26     30 

28.3 

i     45     40.0 

38      6     30 

30.1 

i     46     10.5 

37     59     3° 

26.0 

Dec.    15.9 

7     45     48.2            31      16     50 

+  o.    57     28.1 

oV=+o.ii77  'H'  +0.0841  «V 

H.  T.              7     46    47.1           31     34     20 

30.4 

h.   m.     s.       s. 

7     47     20.2            31     43     10 

28.4 

H(=+o     57  28.7±o.i8 

7     47    43-2           31     49     5O 

28.8 

7     48     28.0 

30     58      o 

30.3 

7    49      o-o 

31       7      o 

30.1 

7     49     25.6            31     13     50 

28.6 

7     49     48.5     :       31     20     30 

29-3 

7     50    36.7     .       3'     33     40 

27.7 

- 

7     51       8-2     '       31     42     50 

28.9 

7     51     35-8     :       31     50     5° 

29.7 

7     52      6-3           3i     59      o 

28.3 

7     53     20.3           33     24     10 

26.5 

7     53     44-5           33     31     10 

27-5 

7     54     15-5 

33    4°      o 

28.3 

7     54    40.5 

33     46     50 

27-7 

REPORT  OF  PROFESSOR  HALL. 


33 


Sextant  Obsfii'<iti<»is — Continued. 


Dale. 

Chronom 

.  1228. 

Sextant 

R. 

C'orr.  chronoin. 
and  latitude. 

Results. 

1870. 

li. 

111. 

S. 

i 

n 

h.    in.       s 

MAMA. 

Dec.    16.1 

i 

37 

40.0 

4" 

M 

o        +  o     57     28 

i 

H.  P. 

i 

3» 

17.0 

40 

4 

20 

29 

i/t——  o.  1289  <//;   —0.0992  (/o 

i 

33 

43-5 

39 

57 

IO 

3i 

ll.      111.            S.                S. 

Ac=+o     57     2g.7±o.i8 

i 

39 

14-5 

39 

49 

20 

30 

S 

i 

4" 

36.0 

38 

23 

40 

30 

3 

i 

41 

S.o 

38 

16 

o 

28 

3 

i 

4i 

41.0 

38 

7 

o 

30 

3 

. 

i 

42 

12.  O 

37 

59 

0 

3« 

5 

i 

43 

16.0 

37 

43 

o                           28  .  5 

i 

43 

39-° 

37 

36 

30 

30 

5 

i 

44 

o-5 

37 

31 

30 

29 

9 

i 

44 

24.0 

37 

25 

o 

29 

8 

i 

45 

38.5 

38 

IO 

50 

29.0 

i 

46 

"•5 

38 

2 

o 

29 

9 

i 

46 

36.0 

37 

56 

IO 

27 

5 

i 

47 

2.O 

37 

4« 

30 

30 

8 

Dec.     16.9 

7 

3i 

M.O 

25 

6 

10 

+   i      o    38.2                                       SYRACUSE. 

II.  H. 

7 

32 

40-5 

25 

3° 

50 

36 

i/l—  -\-O.HTJ  i//i  +0.0830,  to 

7 

34 

6.0 

25 

55 

40 

37 

3 

ll.     111.          S.             S. 

7 

35 

32.5 

26 

21 

10 

39 

3 

Af=  +  i     o     37.4±o.22 

7 

37 

44.0 

28 

3 

30 

38- 

5 

AC=+                1.5 

7 

38 

47-5 

28 

21 

30 

38- 

2 

7 

39 

53-5 

28 

40 

20                                  38. 

6 

7 

41 

23.5 

29 

5 

50                           38. 

7 

1 

42 

52-5 

29 

30 

10                           36. 

3 

1 

43 

53-0 

29 

47 

50                  38. 

9 

7 

45 

14-5 

30 

IO 

0 

36- 

o 

7 

46 

9-5 

30 

25 

20 

36. 

9 

7 

47 

25-5 

29 

4" 

50 

35- 

5 

7 

48 

27.5 

29 

58 

40 

37- 

i 

7 

49 

47-5 

30 

20 

20 

35. 

9 

/ 

7 

50 

20.5 

30 

29 

IO 

35- 

2 

0 

a         •         ii           i, 

Dec.    17.0       10 

51 

31 

59 

40 

40 

+  37       3     54 

?>=  +  37     3     57±i-5 

H.  H. 

10 

52 

39 

59 

41 

10 

53 

10 

53 

32 

59 

41 

20 

52 

IO 

54 

38 

58 

3f> 

50 

42 

IO 

55 

28 

58 

36 

40 

49 

10 

5f> 

It 

58 

36 

25 

56 

' 

10 

57 

20 

58 

36 

o 

OS 

10 

58 

4 

58 

35 

55 

6  1 

IO 

58 

57 

58 

35 

50                           57 

II 

o 

16 

58 

40 

15                            61 

II 

i 

20 

58 

39 

40 

60 

II 

2 

16 

58 

38 

40 

72 

O— E 


34 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 
Sextant  Observations — Continued. 


Date. 

Chronom  1228. 

Sextant  R. 

Corr.  chronom. 
and  latitude. 

Results. 

1870. 

h.    m.        s. 

0                  /                 ,1 

h.     m.      s. 

SYRACUSE. 

Dec.    17.1 

I     53       o.o 

33     43       o 

+   i       o    41.4 

dt=—  0.1220  dh  —  0.0889  <^ 

H.  E. 

I     54     48.5 

33     13     40 

42.4 

h.  m.      s.         s. 

I     55     50.0 

32     57     30 

41.4 

A^=  +  i     o    4O.g±o.ig 

I       56       22.0 

32     48     5° 

41.6 

A/=  —                1.6 

i     57     25-5 

31     27     10 

40.1 

i     58      o.5 

31       17      20 

.    4J-3 

i     58     34-5 

31       8     10 

41.1 

i     59      2.0 

31         0      20 

42.4 

i     59     ?6.o 

3°     45     50 

41.6 

2         O      24  .  0 

3"     39       °                            38.7 

* 

2       i       5-5 

30     27       o 

41-5 

2          I       34.0 

30     19     10 

41.1 

2         2       15.5 

3'      15     50 

39-7 

2         2       40.0 

31       6     10 

40.4 

2         3       10.5 

30     58     10 

38-9 

2       3     48.0 

30     47     30 

40.0 

Dec.    17.9 

7     39       r-° 

28     13     20        +   I       o     36.4 

<#=+o.  1230  dh+o.oqo2  ii<j> 

H.  H. 

7     4"     25.5 

28     37     50                          38.2 

h.  m.     s.        s. 

7     4i     59-° 

29      4     10                          38.0 

Ac=  +  i     o    36.5±o.3O 

7     43     21.5 

29     27     20 

37-8 

A/=  +               1.6 

7    -44    43-o 

28     45     10 

37-6 

7     46      2-5 

29      7     20 

37-7 

7     47     30.o 

29     31     40 

37-7 

7     48     30.5 

29    48      o 

36.7 

7     59      6.0 

33     44     40 

35-9 

8       2       7.5 

34     33     10 

36-5 

8      3     24.5 

34'    54      o 

39-  r 

8  '    4     41.0 

35     12     50 

34-8 

8      6    42.0 

•34     39     30 

36.0 

8       7     57-5 

34     58     10                          33.1 

8      9      9.0 

35     17      o                          34-9 

8     10     13.5 

35     33      o                          33-2 

Dec.    18.1 

i     42       5-5 

36     38      o       +10    42.0 

dt=—  0.1290  M—  0.0983  «<* 

II.  E. 

i     42     37.0 

36     29     10                          45.2 

]].    III.        S.            S. 

i     43       7-5 

36      22      20                                  41.5 

Af—  -j~i     o     41.  8  ±0.22 

i     43     46.0 

35       7     20                            41.9 

A/=-                      T.8 

i     44     17-5 

34    -59     20                           41.6 

i     44     44.0 

34     52     40                            41-' 

i     45       2.0 

34     48      o                          41-2 

i     45     51.5 

34     35      o                          42.1 

i     46     15.0 

34     29     10                           41.2 

i     4fJ     53-5 

34     19       °                           40.7 

i     47     32.5 

35     M      o                          41.5 

i     47     58.5 

35       7     20                          41.0 

i     48     28.0 

34     59   '10                          42.9 

REPORT  OF  PROFESSOR  HALL. 
Sextant  Observations — Continued. 


Dale. 

Chronom.  1228.    Sextant  R. 

Corr.  chronom. 

and  latitude. 

Results. 

1870. 
Dec.  18.9 

h.  m.   s. 
7  23  49.0 

22   33   20 

Ii.   m.   S. 
1-  i   0  38.2 

SYRACIISK. 

H.  E. 

7  27   o.o     23  29  40 

38.8 

#=+0.1145  <«  +0.0783  </<t> 

7  28  14.0     23  51  10 

37-8 

h.  m.   s.    s. 

7  29  22.5     24  n   o 

37-0 

Ar=  +  i  o  37.3±O.I4 

7  32  47.0     26  15  20 

36.5 

A/=  +      1.3 

7  33  17.0     26  24  10 

37.0 

7  33  46.5     26  33   o 

37.8 

7  34  14.5     26  41  10 

38.3 

7  34  52.0  1   26  51  20 

35-8 

7  35  16.5  .   26  58  40 

37-0 

- 

7  35  40.0     27   5  20 

36.4 

7  36   9.0     27  13  20 

37-8 

7   36   57.0      26   22   40 

36.8 

7  37  21.5     26  29  50 

37-4 

• 

7  37  44.5     26  36  20 

37-  2 

7  38   7.5     26  42  40 

36.5 

Dec.  19.0 
H.  H. 

10  47  37       59  30  20 
10  48  38       59  31  50 

+  37   3  68 
.51 

0=  +  37  3  6i±r.8 

10  49  52       59  32  40 

57 

'0  51  13       59  34   o 

50 

10  52  28       58  29  30 

72 

10  53  4i 

58   29   50 

52 

10  54  37       58  30   o 

51 

10  55  33       58  30  30 

42 

10  57   3       58  30   o 

59 

10  58   2       58  29  50 

('4 

10  59   3       58  29  40 

54 

II    O    2 

58  29   o 

7° 

ii   i  40      59  33  50 

57 

ii   2  42       59  32  30 

78 

"   3  44       59  3i  50 

75 

ii   5   o      59  30  45 

75 

Dec.  19.1 

I   48   21.0 

34   i  55 

+  i   o  41.7 

<//=  —  0.1234  dh—  0.0908  (/(» 

H.  H. 

I  49  30  .  o 

33  44   o 

41.2 

h.  m.   s.    s. 

i  50  21.5  !   33  3°  30 

4L5 

A<-=  +  i  o  39-5±o.25 

i  51  22.5 

33  15   o 

39-3 

Af=-      1.7 

i  52  58.5 

33  54  30 

39-9 

i  54   5-0 

33  36  20 

41.8 

i  55  41-5 

33  n   o 

40.2 

i  56  31.0  ' 

32  57  50 

39-9 

i  58  n.  o 

32  31  20 

37-8 

i  59   9-5 

32   15   20 

38.9 

2    O   II.5 

31   58   30 

39-0 

2    2    1.0 

31  29  10 

37-1 

2    2   59.5 

30   7  10 

37-6 

2   4   7-5 

29  48  50 

39-3 

- 

2   4  58.5 

29  35   o 

38.3 

2   5  46  .  o 

2g   21   40 

39-2 

OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 
Sextant  Observations — Continued. 


Date. 

Chronom.  1228. 

Sextant  R. 

Corr.  chronom. 
and  latitude. 

Results. 

1870. 
Dec.    19.3 

h.     m.       s. 

5     54     57.o 

76     51     40 

+  37       3     17 

SYRACUSE. 

H.  H. 

5     56     53-o 

76     53     4° 

73 

,      „ 

5     58       6.5 

76     52     40 

40 

l*=+37     3     39  ±2.  6     I'oiai-is. 

6      o     15.5 

76     52     50 

41 

6       i     47.0 

76     52     50 

39 

6      3     21.5 

76     52     40 

30 

£>      4     37-0 

7<J     53       ° 

40 

• 

6       5     32.5 

76     52     40 

28 

6       9       2.5 

76     53     10 

40 

6     10     13.0 

76     53      o 

34 

6     II       8.0 

76     52     30 

55 

6     II     56.5 

76     53     10 

37 

Dec.    20.3 
H.  H. 

6     32     27.0 
6     35     22.5 

76     52     10 
76     52     20 

+  37       3     19 
2g            0=  +  37     3     3I±2.3     Polaris. 

6     36     56.0 

76     52     30 

38 

6     38     28.5 

76     52     40 

46 

6     40     33-5 

76     52      o 

31 

6     42     50.0 

76     51     50 

32 

6     44     16.0 

7-6     5'     55 

38 

6     45     31.0 

76     51      10 

18 
h.     m.      s. 

Dec.    20.9          7     23     37.5 

23     13     30 

+  i       o     37.5 

(#=+0.1145  '///+0.0783  ifo 

H.  H.             7     24     53.0 

23     36      o 

39-o 

h.   111.       s.         s. 

7     26       9.5 

24       i     40 

37-6 

Ar=+   i     o     38.l±o.26 

, 

7     27     21.0 

24     19     50 

37-6 

A/=+                  1.3 

7     29     43.5 

23     56     50 

37-2 

7     30     54-5 

24     17     30 

36.7 

7     32     36.5 

24    47      o 

35-9 

7     33     46-0 

25       7     30 

37.0 

7     35     38-0 

25     46     10 

38.0 

7     36    49.0 

26        0      20 

37-0 

7     37     59-" 

26     20     50 

38.4 

7     39     n.o 

26     41     50 

39.8 

7     41       2.0 

28     18     20 

39.8 

7     42     10.  o 

28    36    50 

37-2 

7     43       1-5 

28       52       20 

40.6 

7     44     30.0 

29      17      20 

40.8 

Dec.    21.  o       10    45     14.0 

59     22     50 

+   37     3     79         !  0=  +  37     3     6i±i.4 

H.  H.           10    46    47.0 

59     25       o 

74 

10    47     12.5 

59     25     40 

67 

10     47     39.5 

59     26       o 

73 

10     48       6.0 

58      21      50 

59 

10     48     35.5 

58      22      30 

53 

10     49     27.0 

58     23     10 

58 

10     50     53.0 

58      24      20 

58 

10     51     50.0 

58    25     10 

54 

10     52     44.0 

58      25      20 

64 

REPORT  OF  PROFESSOR  HALL. 
Sextant  Observations — Continued. 


37 


' 

Dale.          Chronom.  1228. 

I                                                     ! 

Sextant  R. 

Corr.  chromnn. 
and  latitude. 

Results. 

; 

SYRACUSE. 

1870.              !'•     "I.       s. 

°        '      " 

Dec.    21.0        I0     53     35-0 

58     26     10 

+  37       3     51 

II.  II.            I0     54     35'° 

58       26       20 

59 

II           I          9.0 

59     3i     10 

f>3- 

II       3     10.0 

59     30     1° 

-63 

it       3     42.0 

59     3°     10 

53 

ii       4     29.0 

59     29     30 

56 

h.     m.      s. 

Dec.    21.  i          i     57       9.8 

31     56     20 

+   i       o     39.0 

dt=—  o.  1222  (///—  0.0892  tfy 

H.  T.               i     57     31.1 

31     50    40 

38.9 

h.  m.       s.        s. 

i      57     5i-0 

31     45'    30 

38.2 

A<r=+   i     o     39.i±o.n 

i      58     45.1 

31     31       o 

38.0 

M=-                 1.6 

i     59     28.1 

32     24      o 

39-4 

i     59     50.6 

32     17     50 

39-7 

2        O      22.  O 

32       9     30 

39-0 

2         042.5 

32       4     10 

38.2 

2          I       36  .  I 

31     49     30 

38.5 

2         2         4.7 

31     41     20 

39-9 

2         2      43.0 

31     31     10 

39-2 

2         3       12.6 

31      22      40 

40.4 

2       3     42.0 

30     10       o 

39-1 

2       4      10.4 

3°         2         1  1 

39.9 

2       4     31.5 

29    56    30 

38.7 

2       4     57-5 

29     49     10 

39-4 

• 

li.     m.       s. 

Dec.    21.9          7     30     43.0 

24       5     30 

+    i       o     37.7 

Jt=-\-  o.i  145  <//;+o.o782  i/<ji 

H.T.             7     31     15.7 

24     14     50 

36.9 

li.   m.       s.         s. 

7     3i     37-8 

24       21       3O 

37-4 

At—  +    i     o     35-9±o.25 

7     31     57-5 

24       27       30 

38.3 

A/=  +                 1.3 

7     32     55.2 

25       48      40 

36.8 

7     33     20.7 

25     55     50 

35-9 

7     33     49-5 

26       4     30 

36.8 

7     34     II-5 

26     10     50 

36.7 

7     34     57-5 

26     23     20 

:     33-8 

7     35     20.2 

26     30     10 

34-7 

7     35     44-9 

26     37     20 

34-8 

7     36     10.6 

26.    44     50 

35-1 

7     3f>     42.7 

25     50     20 

39-0 

7     37       M 

25     56     10 

35-1 

7     37     28.7 

26         2       10 

34.1 

7     37     54-8 

26     10      o 

35-2 

7     38     23.0 

26     18       o 

35-0 

1 8 


OBSERVATION'S  OF  THE  ECLIPSE  OF  DEC  K.MHKR  22,  1870. 


The  following  are  the  observations  for  index  correction,  to  which  arc  added  the  observed  values  of  the 
sun's  diameter  compared  with  the  computed  values  : 


Sun's  diameter. 

Date. 

Sextant  readings. 

Index 
correction. 

Difference. 

+        i     26 

Observed. 

Computed 

32    31 

Dec.     :2  9 

o     31     17.5 

359     25     50.0 

32     44 

+   13-1 

13.0 
13-9 

31     25.0         359     25     41.7 
31       6.0          359     25     40.0 

+       I     27 

+        i     37 

32     52 
32     43 

32     33      +   19  1   5 
32     28      +   15  !   | 

14.0 
14.1 

31     21.7          359     25'   46.7 
31     40.6          359     25     21.7 

+       i     26 
+       i     29 

32     47  . 
33       9 

32     32      +   15  f  ^ 
32     30      +  39    2 

14.9 

31     23.3 

359     25     31.7    +       i     32 

32     56          32     29      +27. 

15.0 

31      17.2 

359     26     12.2    +       i     15         32     32         32     32             o 

15.1 

31      16.7 

359     26     16.7  !+       i     13         32     30         32     31              i 

15.9 

31     15.0 

359     26      o.o 

+          I       22 

32     37          32  -   29      +     8 

16.1 

31      15.0 

359     26     20.0 

+          I       12             32       28             32       31 

3 

16.9 

3i       5-0 

359     26     15.0 

+         I      20            32      25 

32     27 

—      2 

17.0 

31     12.5 

359     26       8.3 

+         I      2O 

32     32 

32     33 

I 

17.1 

31       6.3 

359     26      6.3 

+         I      24 

32     30 

32     27 

+     3 

17.9 

31     16.7 

359     26     10.  o 

+         I       17 

32     33 

32     29      +4 

18.1 

3i       3-3 

359     26     16.7 

+         I      20 

32     26 

32     31 

5 

18.9 

3i     12.5 

359     26     13.3 

+         I       17 

32     30 

32     26 

+     4 

19.0 

31     15-8 

359     26     19.2 

+         I       13 

32     28 

32     33 

-     5 

19.1 

•3i     13-3 

359     26     16.7 

+         I       15 

32     28 

32     29 

—      i 

19-3 

359     58     31-7 

+         I      28 

Polaris. 

20.3 

.      .      . 

359     53     36.7 

+         I      23 

Polaris. 

20.9 

3i       5.8 

359     26     10.  o 

+          I       22 

32     28 

32     25 

+     3 

21.  0 

3i     17-5 

359     26       9.1 

+          I       17 

32     34 

32     33 

+     i 

21.  I 

3i     15.0 

359     26     16.7 

+          I       14 

32     29 

32     29 

o 

21.9 

3i       8.3 

359     26     11.7 

+          I       20 

32     28 

32     25 

+     3 

If  we  consider  the  spherical  triangle  formed  by  the  star,  the  zenith  of  the  observer,  and  the  pole  of  the 
heavens,  and  designate  by  A,  S,  /,  the  altitude,  the  declination,  and  hour  angle  of  the  star,  we  shall  have  the 
equation, 

sin  h  =  sin  <p  sin  d  +  cos  <p  cos  3  cos  / 

Since  sextant  observations  for  time  should  be  made  as  near  the  prime-vertical  as  practicable,  the  hour 
angle  will  be  accurately  determined  by  means  of  its  cosine,  and  the  above  simple  formula  is,  I  think,  more 
convenient  for  computation,  and  more  exact  than  the  transformed  expressions  that  are  usually  employed.  For 
the  reduction  of  the  latitude  observations  I  have  used  the  following  formula  derived  from  the  preceding  one 
by  an  easy  transformation  : 

cos  (y>  —  5)  =  sin  //  +  2  cos  tp  cos  S  sin  l/2  fl 
If  we  differentiate  the  first  equation,  considering  d  constant  and  denoting  by  A  the  azimuth,  we  shall  have, 

dr=—          dh  df 

cos  <p  sin  A      cos  <p  tan  A 

This  differential  equation  shows  the  importance  of  making  the  observations  for  time  symmetrical  with 
respect  to  the  meridian.  It  has  been  computed  for  the  mean  hour  angle  in  each  set  of  observations,  dt 
being  expressed  in  seconds  of  time,  and  dh  and  dip  in  seconds  of  arc. 


REPORT  OF  PROFESSOR  HALL. 


39 


At  Malta  my  observing  station  was  at  the  telegraph  office  except  on  the  first  day,  December  13, 
when  the  observations  were  made  a!  Spencer's  Monument.  According  to  the  map  of  the  Ordnance  Survey 
oi  Malta.  Spencer's  Monument  is  253  yards  west  and  2,013  yards  south  of  the  telegraph  office.  In  reduc- 
ing the  observations  made  at  Syracuse  the  latitude  was  assumed  to  be  +37°  3'. 5,  and  a  reduction,  J/,  to  the 
latitude  finally  adopted,  is  given  in  the  column  of  results. 

Tli'.-  following  are  the  values  of  the  latitudes  obtained  from  the  sextant  observations  : 


Malta,  Spencer's  monument, 
Malta,  telegraph  office, 

Syracuse,  Bastione  San  Filippo, 
Syracuse,  Bastione  San  Filippo, 
Syracuse,  Bastione  San  Filippo, 
Syracuse,  Bastione  San  Filippo, 
Syracuse,  Bastione  San  Filippo, 

Mean  latitude, 


v  = 

+  35 

52 

55; 

f  — 

+  35 

54 

^  I    ? 

(p  -  — 

+  37 

3 
3 
3 

57! 
61; 
61; 

3 

395 

3 

31  ; 

1 6  altitudes  of  the  sun, 

20  altitudes  of  the  sun. 

12  altitudes  of  the  sun. 

1 6  altitudes  of  the  sun. 

16  altitudes  of  the  sun. 

1 2  altitudes  of  Polaris. 

8  altitudes  of  Polaris. 


3     48 


Corrections  of  Chr<>noi>tftfr  Xc^us  1228  on  Local  Mean  '/}'/>/<•. 


Place. 

Date. 

A.  M. 

P.  M. 

Mean. 

1870. 

h.    m.        s. 

h.    m.        s. 

h.    in.        s. 

Mali.i     .    . 

Dec.    13 

+     o     57     29.6 

14    +     o     57     28.4 

+     o     57     28.6    +     o     57     28.5 

15    +     o     57     28.0 

+     o     57     29.2    +     o     57     28.6 

16    +     o     57     28.7 

+     o     57     29.7  •  +     o     57     29.2 

Syracuse   . 

Dec.     17 

+     i       o     38.9 

+     i       o     39.3 

+     I       o     39.1 

j              -IS 

-1-     i       o     38.1 

+10     40.0 

+     I       o     39.0 

19 

+10     38.6 

+     10     37.8    +      i       o     38.2 

21 

+     i       o     39.4 

+     i       o     37-5    +     i       o     38.4 

22 

+  .    i       o     37.2 

When  at  Malta  I  was  permitted  by  M.  Berthet  to  use  his  transit-instrument.  This  instrument,  made 
by  Secretan,  of  Paris,  in  1862,  has  an  objective  of  three  inches,  and  is  very  well  mounted  in  an  observatory 
on  St.  James  Cavalier,  the  meridian  of  which  differs  but  little  from  that  of  the  telegraph  office.  As  the 
value  of  the  level  divisions  had  not  been  determined,  the  level,  and  also  the  collimation  error,  were  made 
zero  by  M.  Berthet  a  short  time  before  the  observations.  The  wires  of  the  instrument  were  too  thick  to 
admit  of  very  accurate  observations  of  transits,  but  the  following  may  serve  as  a  check  on  the  determina- 
tions of  time  with  the  sextant  : 


Date. 

Star.             \Vin-s. 

Chron.  1228. 

A  pp.  a. 

Corr.  chron. 

1870. 

h.      m.       s. 

h.    m.         s. 

li.    m.         s. 

December  14 

;•  »cti  ....          5 

S       5     59-44 

2     36     36.84 

+  o     57     28.48 

a  Ceti  ....          5 

S     24     5  i  .  74 

2     55     32.10 

57     28.33 

6  Arietis     .    .          5 

S     33     33-38 

3       4     15-16 

57     28.32 

a  Persei  ...          5 

S     44     23.74 

3     15       7-54 

57     28.55 

December  15  j   12  Ccti  ....          5 

5     49     I4-76 

o     23     26.40 

+  o     57     29.59 

i)  Ceti  ....          5       6      2     52.30 

o    37       5.82 

57     29.46 

y  Cassiopex  .          5 

6     14     38.66 

o    48     56.20 

57     29-69 

£  Piscium  .    .          5 

6     21     56.88 

o     56     14.30 

57     28.74 

Polaris    .    .          3 

6     37       2. 

I    II    58. 

57     29. 

'     v  Piscium  .    .          5 

7       o     i  9  .  40 

I     34     42.59 

57     29.31 

',   Arietis    .    .          5 

7     '3       5-20 

'     47     30.51 

57     29.  09 

OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


TKI,K<;RAPHIC  SIGNALS  FOR  I,O.\<;ITI :m  . 

Through  the  kindness  of  Mr.  Rosenbusch  the  telegraph  offices  at  Malta  and  Syiacuse  were  furnished 
with  small  portable  and  very  convenient  instruments  for  sending  and  receiving  the  signals.  Each  instru- 
ment was  provided  with  two  keys,  worked  by  the  observers,  and  the  signals  were  given  by  the  observer 
striking  his  key  in  coincidence  with  the  beat  of  his  chronometer.  The  signals  were  recorded  on  a  fillet  of 
paper  similar  to  that  used  with  the  Morse  register.  For  example,  the  observer  at  Syracuse  gave  signals 
every  fifth  second  of  his  chronometer  for  three  minutes,  the  observer  at  Malta  during  the  same  time  giving 
signals  at  every  second  of  his  chronometer,  and,  both  sets  of  signals  being  recorded  on  the  fillet  of  the 
Malta  instrument,  a  very  accurate  comparison  of  the  chronometers  was  obtained.  The  operation  was  then 
reversed,  the  observer  at  Malta  sending  signals  every  fifth  second  to  Syracuse,  and  the  chronometers  were 
compared  on  the  fillet  of  the  Syracuse  instrument.  The  following  are  the  results  of  the  readings  of  the  fillets. 
At  Syracuse  the  signals  were  made  by  Professor  Harkness,  who  used  the  chronometer  Negus  1115.  At 
Malta  I  used  the  chronometer  Negus  1228. 


Dale. 

Malta 

fillet. 

Syracuse 

fillet. 

Ch.  1228—  Ch 

.  IU5 

Ch.  1228—  Ch 

I.II5 

1870. 

h. 

in 

s. 

in. 

s. 

Dec 

•  13. 

0.4               +         2 

4 

22                        + 

2 

4- 

23 

14. 

3-3 

+          2 

4- 

44                   + 

2 

4- 

47 

15, 

3-5 

+         2 

4- 

79                  + 

2 

4- 

So 

16, 

I.I               +         2 

5- 

25                  + 

2 

5- 

23 

If  we  denote  by  c  and  c1  the  chronometer  times  when  the  signal  was  sent  and  received,  and  by  Ji  and 
Ac'  the  corrections  of  the  chronometers,  the  difference  of  longitude  will  be, 

c  —  f'  +  Ji- —  Jf'  +  c 

where  £  is  the  time  required  for  the  signal  to  pass  from  one  station  to  the  other.  The  present  observations 
do  not  furnish  data  for  the  determination  of  s,  and  its  further  consideration  is  omitted.  The  preceding 
table  gives  the  values  of  c— c1,  and  Professor  Harkness  has  furnished  the  corrections  of  the  chronometer 
Negus  1115.  Collecting  the  necessary  quantities,  we  have  the  following  results  for  the  difference  of  longi- 
tude between  the  telegraph  office  in  Malta  and  our  station  in  Syracuse: 


Date. 

Corr. 

ch. 

1228. 

Corr. 

ch. 

1115.            c—c 

* 

1870. 

h. 

m. 

s. 

h. 

in. 

S. 

m.      s. 

111.        .s 

December 

13 

+       0 

57 

28.3 

+     i 

2 

43.2     +         2      4;2     - 

3     10. 

7 

14 

+     o 

57 

28.5 

+     i 

2 

44-0 

+          2      4.4     - 

3     ii  • 

i 

IS 

+     o 

57 

28.7 

;+     * 

2 

44-4 

+         2      4.8    - 

3     io. 

9 

16 

+       0 

57 

29.2 

•'+     i 

2 

44-7 

+         2      5.2     - 

I 

3     io. 

3 

Taking  the  mean  of  these  results,  we  have  Syracuse  east  of  Malta 

3'"  ios.  j  ±  o«.33 

Omitting  all  consideration  of  personal  equation  in  'sending  the  signals,  the  comparison  of  the  chronometers 
by  means  of  the  telegraph  may  be  considered  as  exact,  since  from  1 64  comparisons  it  results  that  the  prob- 
able error  of  a  single  comparison  is  only  ±o8.c>34.  From  the  240  altitudes  observed,  I  find  that  the  prob- 


REPORT  OF  PROFESSOR  HALL. 


able  error  of  one  of  my  time  determinations  from  the  mean  of  12  altitudes  is  -to8. 2  7.  On  the  other  hand, 
the  sun  was  observed  at  azimuths  of  about  forty  degrees  only  east  and  west  of  the  meridian,  and  the  dif- 
ferential equations  show  that  an  error  of  10"  in  the  altitude  will  produce  an  error  of  more  than  one  second 
in  the  time.  From  these  considerations  I  estimate  the  probable  error  in  the  difference  of  longitude  to  be 
one  third  of  a  second. 

The  following  is  the  record  of  the  signals  exchanged  with  Professor  Newcomb,  who  was  at  Gibraltar.  In 
sending  the  signals,  the  observer  struck  the  telegraph  key  in  coincidence  with  the  beat  of  his  chronometer. 
The  signals  were  received  in  the  following  manner :  A  telegraph-operator  watched  the  bright  image  of  the 
mirror,  and  at  the  instant  he  observed  a  motion  of  the  image  he  struck  a  key  that  gave  a  sharp  click,  and 
the  time  of  this  click  was  observed  on  the  chronometer  at  Gibraltar  by  Professor  Newcomb,  and  at 
Malta  by  myself. 

Record  of  Signals. 


MALTA   RECORD. 

GIBRALTAR   RECORD. 

Date. 

Chron.  1228. 

Chron.  1265. 

Difference. 

Date. 

Chron.  1265. 

Chron.  1228. 

Difference. 

1870. 
Dec.    15 

h.    m.        s. 
4     45       0.6: 

h.    m.        s. 
4     45     15-0 

m.       s. 
o     14.4: 

1870. 
Dec.  15 

h.   m.        s. 
4     52     17-7? 

h.    m.     s. 
4     52       o 

m.       s. 
o     17.7? 

45     15.6: 

45     30-o 

14.4: 

52     32.0? 

52     15 

17.0? 

45     29.5 

45     45-0 

15.5 

52     47.1 

52     30 

17.1 

45     43-5 

46       o.o 

16.5 

53      2.4 

52     45 

17-4 

45     58.5 

46     15.0 

16.5 

53     17.4 

53       o 

17-4 

46     13-5 

46     30.0 

16.5 

53     32.4 

53     15 

17.4 

46     28.6 

46     45.0 

16.4 

53    47-3 

53     3° 

17.3 

46     43-5 

47       o.o 

16.5 

54      2.5 

53     45 

17-5 

46     58.6 

47     15-0 

16.4 

54     17-3 

54       o 

17.3 

47     14-5 

47     30-0 

15-5 

54     32.3 

54     15 

17-3 

47     28.7 

47     45-0 

16.3 

54     47-3 

54     30 

17-3 

47     43-5 

48       o.o 

16.5 

55         2.2 

54     45 

17.2 

47     58.6 

48     15.0 

16.4 

55     17-3 

55       o 

17.3 

48     13-5 

48     30.0 

16.5 

55     32.4 

55     15 

17.4 

48     28.6 

48     45.0 

16.4 

55    (47.3)? 

55     30 

17-3? 

48     43-5 

49       o.o 

16.5 

56      2.5 

55     45 

17.5 

48     58.5 

49     15-0 

16.5 

56     17.3     '                56      o 

17.3 

49     13-6 

49     30.0 

16.4 

56     32.2 

56     15 

17.2 

49     29.0 

49     45.0 

16.0 

56    47-4 

56     30 

17.4 

49     43-5 

50       o.o 

16.5 

57       2.4 

56     45 

17-4 

57     17-4 

57       o 

17.4 

Mean,  (18,)  o1"  i6».32±os.oi6 


Mean,  (18,)  om  I78.34±o8.oo6 


ft— E 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 
Record  of  Signals — Continued. 


MALTA    RECORD. 

GIBRALTAR    RECORD. 

Date. 

Chron.  1228. 

Chron.  1265. 

Difference. 

Date. 

Chron.  1265. 

Chron.  1228. 

Difference. 

1870. 

h.      m.        s. 

h.     m.        s. 

m.      s. 

1870. 

h.     m.        s. 

h.      m.      s. 

m.       s. 

Dec.    16 

ii     31     43.2 

23     32      o.o 

0     16.8 

Dec.  16        23     39    (18.7): 

ii     39       o 

o     18.7: 

31     58.0 

32     15-0 

17.0 

39     32.7: 

39     15 

17.7: 

32     13.0 

32     30.0 

17.0 

39    48.o: 

39     30 

iS.O: 

32     28.0 

32     45.0 

17.0 

40      3.0 

39     45 

18.0 

32     43-° 

33       o.o 

17.0 

40     17.9: 

40      o 

17.9. 

32     58.0 

33     15-0 

17.0 

40     33-o 

40     15 

18.0 

33     13-0 

33     30.0 

17.0 

40    48.1 

40     30 

18.1 

33     28.1 

33     45-° 

16.9 

4i       3-2 

40     45 

18.2 

33     43-0 

34      o-o 

17.0 

41       lS.2 

41       o 

18.2 

33     57-9 

34     i5-o 

17.1 

41    33.2 

41     ^ 

18.2 

34     13-0 

34     30.o 

17.0 

41     48.1 

41    30 

18.1 

34     28.0 

34    45-o 

17.0 

42     3.2 

41     45 

lS.2 

34     43-0 

35      o-o 

17.0 

42     18.0 

42       o 

iS.o 

34     58.2 

35     15-0 

16.8 

42     33-o 

42     15 

18.0 

35     13-0 

35     3°-° 

17.0 

42     48.1 

42     30 

18.1 

35     28.2 

35     45-0 

16.8 

43      3-2 

42     45 

18.2 

35     43-1 

36      o.o 

16.9 

43     18.3 

43       o 

18.3 

35     58.o 

36    15.0 

17.0 

43     33-2 

43     15 

18.2 

36     13.0 

36    30.0 

17.0 

43     48.1 

43     30 

18.1 

36     28.2 

36    45.0 

16.8 

44       3-0 

43     45 

iS.o 

36    43-1 

37      o.o 

16.9 

44     18.3 

44       o 

18.3 

Mean,  (21.)  om  i6'.95±o-.oo4  Mean,  (17,)  om  i8«.i3±o".oo5 

Hence  collecting  the  quantities  and  using  the  corrections  of  chronometer  1265  found  by  Professor  New- 
comb,  we  have  the  following  results  : 


Date. 

Corr.  chron.  1228. 

Corr.  chron.  1265. 

c  —  c 

A?. 

1870. 
DJC.  15 
16 

h.  m.    s. 
+   o  57  28.7 
+   o  57  29.2 

h.  m.   s. 
—   o  22  16.5 
—   o  22  15.3 

m.   s. 
—   o  16.8 

-   o  17.5 

h.  m.    s. 
-  19  28.4 
I  19  27.0 

The  determination  of  time  at  Gibraltar,  on  December  16,  is  from  an  observation  of  a.  Lyre,  while  the 
determination  of  the  1  5th  is  from  four  observations  east  and  west  of  the  meridian,  and  is  therefore  much 
more  trustworthy.  I  adopt,  as  the  difference  of  longitude, 


ih  19 


If  we  reject  the  time  determination  of  December  16  at  Gibraltar,  and  assume  a  constant  rate  of  the 
chronometer  from  the  isth  to  the  igth,  the  resulting  longitude  for  the  i6th  will  be  ih  19™  28".  5  ;  but  this 
process  does  not,  I  think,  add  any  weight  to  the  adopted  value. 

As  indicated  by  the  date,  the  principal  part  of  the  preceding  report  was  written  immediately  after  my 
return  home  and  before  I  had  seen  any  reports  or  discussions  of  the  observations  in  Sicily.  A  small  part 
of  the  numerical  reductions  could  not  be  completed  until  I  had  received  from  Professors  Newcomb  and 
Harkness  their  determinations  of  local  time. 

Verv  respectfully,  your  obedient  servant, 

ASAPH  HALL, 
Professor  of  Mathematics,  U.  S.  N. 

Commodore  B.  F.  SANDS,  U.  S.  N., 

Superintendent  U.  S.  Naval  Observatory,  Washington,  D.  C. 


REPORT 


PROFESSOR  WM.  HARKNESS,  U.  S.  N. 


REPORT    OF    PROFESSOR    WM.    HARKNESS,    U.  S.  N. 


UNITED  STATES  NAVAL  OBSERVATORY, 

Washington,  J-uly  13,  1871. 

SIR:  In  accordance  with  orders  from  the  Navy  Department,  dated  September  16,  1870,  I  have  the 
honor  to  submit  to  you  the  following  report  in  relation  to  the  astronomical  and  other  observations  made 
by  me  in  connection  with  the  expedition  sent  to  Sicily,  by  this  Observatory,  for  the  purpose  of  observing 
the  total  solar  eclipse  of  the  22d  of  December  last. 

I.— INTRODUCTORY. 

I  left  Washington  at  9  p.  m.,  October  28,  arriving  in  New  York  early  the  following  morning.  The  next 
three  days  were  spent  in  arranging  details  regarding  the  transportation  of  the  officers  and  instruments  of  the 
party,  and  at  2  p.  m.,  November  2,  Professors  Hall,  Eastman,  and  I,  sailed  from  Jersey  City  in  the  Cunard 
steamer  China.  After  an  unusually  rough  and  disagreeable  passage  we  arrived  safely  in  Liverpool  at  1 2.30 
p.  m.,  November  13.  We  had  with  us  no  less  than  ten  cases  of  instruments,  all  of  which  were  most  cour- 
teously passed  through  the  custom-house  without  being  opened,  and  without  a  moment's  delay,  the  authori- 
ties saying  that  they  had  received  orders  from  the  government  at  London  to  do  so.  At  4.45  p.  m.,  Novem- 
ber 15,  Mr.  Alvan  Clark,  jr.,  and  I,  left  Liverpool  by  rail  for  York,  where  we  spent  the  night.  The  next 
morning  we  visited  the  works  of  Messrs.  T.  Cooke  &  Sons,  and  in  the  afternoon,  by  appointment,  we  met 
Professor  Newcomb  at  the  railway  station,  and  went  on  with  him  to  Newcastle,  and  thence  to  Gateshead, 
for  the  purpose  of  seeing  Mr.  Newall's  gigantic  refracting  telescope. 

While  on  the  train,  Professor  Newcomb  told  me  that  he  had  selected  Gibraltar  as  the  most  suitable 
station  from  which  to  make  his  observations  on  the  eclipse,  and  that  he  had  made  all  necessary  arrange- 
ments with  the  Astronomer  Royal,  and  with  the  various  telegraph  companies  whose  wires  would  be  required, 
to  exchange  longitude  signals  between  Greenwich  and  that  place.  He  also  added  that  he  had  informed 
the  managing  directors  of  the  submarine  cables  that  it  was  probable  I  would  be  desirous  of  determining  the 
difference  of  longitude  between  Gibraltar  and  my  station  at  Syracuse,  and  that  they  had  expressed  their 
entire  willingness  to  grant  me  the  free  use  of  their  wires  for  that  purpose  if  I  would  make  known  my  wishes 
to  them.  Accordingly,  when  I  subsequently  passed  through  London,  on  my  way  to  Southampton,  I  called 
on  W.  T.  Ansell,  esq.,  secretary  of  the  Falmouth,  Gibraltar,  and  Malta  Telegraph  Company,  and  he  intro- 
duced me  to  Sir  James  Anderson,  managing  director  of  that  company,  and  also  of  the  Anglo-Mediterranean 
Telegraph  Company.  These  gentlemen  treated  me  with  the  greatest  kindness,  evincing  a  deep  interest  in 
our  scientific  operations,  and  showing  a  very  strong  desire  to  do  all  in  their  power  to  insure  our  success. 
They  at  once  granted  me  the  free  use  of  their  cables  for  the  exchange  of  longitude  signals,  and  furnished 
me  with  a  letter  of  introduction  to  Benjamin  Smith,  esq.,  their  superintendent  at  Malta,  requesting  him  to 
afford  me  every  possible  facility.  In  addition,  Sir  James  Anderson  wrote  a  note  to  Edward  Tombs,  esq., 
secretary  of  the  Mediterranean  Extension  Telegraph  Company,  who  own  the  submarine  cable  between 
Malta  and  Sicily,  requesting  him  to  grant  me  the  free  use  of  their  line,  and  to  furnish  me  with  a  letter  of 
introduction  to  Edward  Rosenbusch,  esq.,  their  engineer  and  general  superintendent  at  Malta.  This  was  at 
once  done,  and  I  here  desire  to  offer  my -thanks  to  all  the  above-named  gentlemen  for  their  liberality  in  the 
cause  of  science. 

At  3  p.  m.,  November  26,  our  party  sailed  from  Southampton  on  the  Peninsular  and  Oriental  Com- 
pany's steamer  Poonah.  During  the  voyage  we  touched  at  Lisbon  and  Gibraltar,  and,  after  a  tolerably 
pleasant  passage,  we  landed  at  Malta  about  12.30  a.  m.,  December  6.  A  day  or  two  before  arriving  at  the 
last  mentioned  place  I  became  slightly  acquainted  with  one  of  my  fellow  passengers,  who  manifested  some 
irfterest  in  our  expedition,  and  who,  upon  learning  that  we  contemplated  using  the  telegraph  cables  for  lon- 
gitude purposes,  said  that  he  was  a  director  in  the  company,  and  that  when  we  got  to  Malta  he  would  go 


46  OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 

on  shore  and  request  their  superintendent  to  afford  me  all  possible  assistance.  He  fulfilled  his  promise  at 
the  expense  of  no  little  personal  inconvenience,  for  the  Poonah  reached  Malta  about  half  an  hour  after 
midnight  and  departed  about  daylight  the  following  morning.  While  on  board  ship  I  was  ignorant  of  the 
gentleman's  name,  but  the  superintendent  at  Malta  subsequently  told  me  that  it  was  Mr.  Elliot,  of  the  well- 
known  firm  of  Glass,  Elliot  &  Co.,  and  I  here  desire  to  offer  him  my  thanks  for  his  kind  interest  in  the  wel- 
fare of  our  expedition. 

For  the  better  understanding  of  what  follows,  it  may  be  well  to  give  some  details  as  to  the  ownership 
and  management  of  the  telegraph  lines  which  we  proposed  to  use  in  determining  differences  of  longitude. 
The  land  lines  from  the  Greenwich  Observatory  to  Porthcurno  are  owned  and  controlled  by  the  English 
government,  R.  S.  Culley,  esq.,  being  the  engineer-in-chief.  The  submarine  cables  from  Porthcurno  to 
Lisbon,  from  Lisbon  to  Gibraltar,  and  from  Gibraltar  to  Malta,  are  owned  and  controlled  by  the  Falmouth, 
Gibraltar,  and  Malta  Telegraph  Company,  Sir  James  Anderson,  managing  director,  Benjamin  Smith,  esq., 
superintendent  at  Malta.  The  submarine  cable  from  Malta  to  Modica,  in  Sicily,  is  owned  and  controlled 
by  the  Mediterranean  Extension  Telegraph  Company,  Edward  Tombs,  esq.,  secretary,  Edward  Rosen- 
busch,  esq.,  engineer  and  general  superintendent,  residing  at  Malta.  The  land  lines  from  Modica  to  Flor- 
ence are  owned  by  the  Italian  government,  but  one  of  the  wires  is  leased  to  and  controlled  and  worked 
by  the  Anglo-Mediterranean  Telegraph  Company,  Sir  James  Anderson,  managing  director,  Edward  Rosen- 
busch,  esq.,  engineer  and  general  superintendent.  Syracuse  is  on  the  line  from  Modica  to  Florence.  It 
will  thus  be  seen  that  in  working  from  Malta  to  Syracuse  we  would  be  using  the  wires  of  two  different  com- 
panies, but,  as  Mr.  Rosenbusch  is  engineer  and  general  superintendent  of  both,  the  whole  line  is  under  the 
control  of  one  man. 

On  the  morning  of  December  6  I  made  inquiries  as  to  where  the  offices  of  the  various  telegraph  com- 
panies were  to  be  found  in  Malta,  and  was  told  that  they  were  all  in  the  same  building.  I  also  learned  that 
Mr.  Smith,  local  superintendent  of  the  Falmouth,  Gibraltar,  and  Malta  line,  boarded  at  Dunsford's  Hotel, 
where  I  was  then  staying.  Accordingly,  I  called  on  him  in  his  room,  and  presented  my  letter  of  introduc- 
tion. He  received  me  very  kindly,  and  took  me  to  the  telegraph  office,  where,  after  showing  me  everything, 
he  placed  a  clerk  and  a  complete  set  of  the  company's  apparatus  at  my  disposal,  in  order  that  I  might 
become  quite  familiar  with  it,  as  it  was  very  different  from  the  apparatus  employed  in  the  American  telegraph 
offices.  He  assured  me  that  there  would  not  be  the  least  difficulty  in  exchanging  signals  between  Malta 
and  Gibraltar,  and  that  the  only  thing  necessary  was  for  me  to  designate  what  apparatus  I  wished  used  and 
how  I  would  have  it  handled  during  the  longitude  work.  This  I  did,  and  I  have  to  thank  him,  and  the 
gentlemen  attached  to  his  staff,  for  their  very  efficient  assistance  in  carrying  out  our  operations. 

I  next  called  on  Mr.  Rosenbusch,  engineer  and  general  superintendent  of  the  Mediterranean  Extension 
Telegraph  Company,  and  of  the  Anglo-Mediterranean  Telegraph  Company — a  gentleman  whom  I  subse- 
quently learned  to  know  as  one  of  the  kindest  and  best  friends  that  it  was  my  good  fortune  to  meet  during  my 
absence  abroad.  He  told  me  that,  so  far  as  the  Malta  end  of  the  line  was  concerned,  there  would  not  be  any 
difficulty,  for  he  was  ready  to  do  anything  that  I  might  deem  necessary;  but  that  at  Syracuse  the  case  was 
different,  because  the  wire  controlled  by  his  company  is  a  through  one,  and  their  contract  with  the  Italian 
government  only  permits  them  to  have  offices  at  Modica  and  Florence.  Hence,  as  all  telegraph  offices  in 
Italy  are  controlled  by  the  government,  it  would  be  necessary  to  secure  its  assent  before  it  would  be  possi- 
ble for  us  to  use  the  company's  wire  between  Modica  and  Syracuse.  In  order  to  procure  this  assent,  Mr. 
Rosenbusch  at  once  telegraphed  to  Florence  to  Commendatore  Ernest  d'Amico,  director  general  of  the 
Royal  Italian  telegraph  lines,  and  in  twenty-four  hours  I  had  the  satisfaction  of  learning  that  Signer 
Emmanuele  Astor,  sub-inspector  of  the  Royal  Italian  telegraphs,  had  been  ordered  to  proceed  to  the 
telegraph  office  at  Syracuse,  and  there  to  give  us  every  possible  facility  for  exchanging  longitude  signals  with 
Malta.  Moreover,  as  Signer  Astor  and  the  other  telegraph  officials  whom  I  would  meet  at  Syracuse  spoke 
only  Italian,  a  language  of  which  I  know  very  little,  Mr.  Rosenbusch  kindly  volunteered  to  accompany 
me  to  overcome  all  difficulties  that  might  arise  on  that  score,  and  to  give  me  the  benefit  of  his  influence 
with  various  government  officers  at  Syracuse,  all  of  whom  were  his  personal  friends. 

I  was  now  ready  to  proceed  to  Syracuse,  but,  as  the  steamer  was  not  advertised  to  sail  until  Friday 
evening,  I  amused  myself  during  the  interval  of  waiting  by  visiting  the  various  objects  of  interest  in  and 
around  Malta.  And  here  I  must  not  omit  to  mention  that  my  pleasure  in  so  doing  was  greatly  enhanced 
by  numerous  kind  attentions  shown  me  by  our  consul,  Lyell  T.  Adams,  esq.,  and  our  vice-consul,  William 
John  Stevens,  esq. 


REPORT  OF  PROFESSOR  HARKNESS.  47 

The  Malta  channel  is  often  very  rough,  and  at  such  times  the  small  steamers  of  the  Florio  line,  which 
carry  the  mails  between  Malta  and  Sicily,  do  not  venture  to  cross.  Unfortunately  for  us,  Wednesday, 
Thursday,  and  Friday  were  quite  stormy,  and  when  we  went  to  bed  on  Saturday  night  the  steamer  had 
not  yet  arrived.*  At  6  o'clock  on  Sunday  morning,  December  n,  I  was  awakened  by  the  joyful  tidings 
that  the  mail-steamer  had  just  come  in,  and  that  she  would  depart  for  Syracuse  as  soon  as  her  freight  could 
be  got  on  shore.  I  dressed  rapidly,  but  there  was  much  delay  in  getting  breakfast,  and  I  was  afraid  the 
steamer  would  be  oft"  without  us.  The  fear  was  groundless.  I,  in  company  with  Professor  Eastman  and 
Mr.  Rosenbusch,  was  on  board  at  9  o'clock,  and  she  did  not  sail  till  a  quarter  before  n.  She  was  the 
Corriere  Siciliano — a  nice  little  boat — and  after  a  very  pleasant  passage  of  about  eight  hours,  she  landed  us 
in  Syracuse  at  7  o'clock  in  the  evening.  Professor  Hall,  in  company  with  Dr.  C.  H.  F.  Peters,  of  the  United 
States  Coast  Survey  Eclipse  Expedition,  had  gone  over  to  Sicily  on  December  6,  and  had  secured  on  our 
behalf  the  kind  offices  of  our  consular  agent,  N.  Stella,  esq.,  and  of  the  English  consul,  Nicolo  Bisani,  esq. 
These  gentlemen  met  us  at  the  custom-house,  and,  thanks  to  them  and  to  Mr.  Rosenbusch,  our  personal 
baggage  was  passed  without  being  opened,  and  we  went  at  once  to  the  Albergo  della  Vittoria,  where  we 
were  furnished  with  pleasant  quarters,  and  made  very  comfortable  during  our  stay  in  Syracuse. 

About  8  o'clock  the  same  evening  Mr.  Rosenbusch  and  I  visited  the  telegraph  office  in  Syracuse,  where 
we  met  Signor  Emmanuele  Astor,  sub-inspector  of  Royal  Italian  telegraphs,  Signor  Raffaele  Spagna,  super- 
intendent of  the  Syracuse  office,  and  Signor  Mario  Lanza,  assistant  in  the  Syracuse  office.  We  found  these 
gentlemen  willing  to  do  everything  in  their  power  for  us,  and  after  a  little  consultation  all  the  details  relative 
to  the  exchange  of  longitude  signals  were  satisfactorily  arranged. 

At  12.30  p.  m.,  December  12,  Professor  Eastman,  Mr.  Rosenbusch,  and  I,  made  an  official  visit  to 
Chevalier  Achille  Basile,  royal  prefect  of  the  province  of  Syracuse,  who  received  us  most  kindly,  and  said 
that  it  would  afford  him  the  greatest  pleasure  to  be  of  service  to  us  while  we  remained  in  Syracuse.  That 
same  afternoon  he  had  the  boxes  containing  our  instruments  passed  jthrough  the  custom-house  without  being 
opened,  and  delivered  to  us  at  our  hotel. 

II.— SITE  OF  OBSERVING-STATION. 

After  making  a  thorough  reconnaissance  of  the  whole  city  of  Syracuse,  the  place  which  seemed  to  me 
best  adapted  for  our  observing-station  was  the  bastion  situated  on  the  north  side  of  the  Prima  Porta  Terra. 
The  surface  of  the  ground  there  was  52  feet  above  the  sea-level,  and,  with  the  exception  of  an  arc  of  55°, 
included  between  the  true  bearings  S.  5°  W.  and  S.  50°  E.,  the  horizon  was  perfectly  unobstructed.  The 
obstructions  in  the  arc  in  question  consisted  of  the  buildings  in  the  more  elevated  part  of  the  city,  but  they 
nowhere  rose  so  high  as  to  interfere  with  astronomical  observations. 

I  accordingly  wrote  a  note  to  the  Prefect,  requesting  to  be  permitted  to  occupy  the  bastion  as  our 
observing-station,  and  asking  for  the  loan  of  two  tents  to  shelter  our  instruments.  He  replied  that  the 
bastion  was  at  our  service,  and,  if  we  wished,  he  would  also  give  us  the  use  of  a  large  empty  store-house  in 
it.  As  our  instruments  were  all  so  portable  that  it  was  not  necessary  to  leave  them  in  position  during  the 
night,  the  store-house  was  much  better  adapted  to  our  wants  than  tents  would  have  been,  and  I  gladly 
accepted  it.  At  9  a.  m.,  December  13,  the  Prefect  sent  an  officer  of  his  staff  to  take  us  to  the  bastion,  to 
put  us  in  possession  of  the  store-house,  and  to  inform  us  that  he  would  have  a  military  guard  detailed,  whose 
duty  it  would  be  to  see  that  no  injury  came  to  our  property.  That  same  morning  we  had  our  boxes  sent 
from  the  hotel  to  the  store-house,  got  our  instruments  unpacked,  and  began  observing.  During  the  forenoon 
the  guard  arrived,  and  from  that  time  till  we  left  Syracuse  there  was  always  a  sentinel  at  the  door  of  the 
store-house. 

On  the  evening  of  December  16,  Messrs.  A.  Brothers  and  Alfred  Fryer,  of  the  English  Eclipse  Expedition) 
arrived  in  Syracuse ;  and  on  the  morning  of  December  21,  Mr.  George  Griffith,  also  of  the  English  expedition, 
arrived.  By  our  invitation,  and  with  the  consent  of  the  Prefect,  these  gentlemen  occupied  the  bastion  and 
store-house  in  common  with  us  as  an  observing-station. 

*  There  are  often  very  great  delays,  occasioned  by  rough  weather,  in  getting  from  Malta  to  Sicily,  and  as  there  was  every 
appearance  that  we  were  to  be  the  victims  of  one  of  them,  at  a  time  when  it  was  very  important  that  we  should  get  speedily  to 
Syracuse,  in  order  to  determine  our  longitude,  on  Friday  Vice-Admiral  Sir  Hastings  Reginald  Yelverton,  K.  C.  B.,  com- 
mander-in-chief  of  H.  B.  M.  Mediterranean  squadron,  sent  a  message  to  us  through  our  consul,  saying  that  if  the  mail-steamer 
did  not  arrive  by  Monday,  he  would  on  that  day  send  us  to  Syracuse  in  his  own  dispatch-vessel,  the  Psyche.  Such  generosity 
should  not  be  passed  over  in  silence,  and  it  gives  me  pleasure  to  offer  the  thanks  of  the  party  to  Vice- Admiral  V'elverton. 


48 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


Figure  i,  drawn  on  a  scale  of  i  to  2500,  shows  the  exact  positions  occupied  by  the  instruments  of  the 
different  observers  in  the  bastion.  The  point  P  is  directly  over  the  key-stone  in  the 
east,  or  city,  face  of  the  arch  over  the  Prima  Porta  Terra,  i  is  a  stone  gun-plat 
form,  which  was  situated  near  the  northern  end  of  the  western  face  of  the  bastion. 
On  it  were  made  the  observations  for  time  and  latitude,  and  on  the  day  of  the 
eclipse  Professor  Hall's  telescope  stood  upon  it.  H  and  E  indicate,  respectively, 
the  position  of  my  telescope  and  of  that  of  Professor  Eastman.  B  is  the  position 
of  Mr.  Brothers's  photographic  telescope.  Mr.  Griffith's  telescope  stood  between 
E  and  B.  The  following  are  the  measured  distances,  corrected  for  error  in  length 
of  tape-line  : 

i  to  H  =    34  feet  =  10.4  meters. 
i  to  E  =  no  feet  =  33.5  meters, 
i  to  B  =226  feet  =  68.9  meters. 
The  angles  at  i  were 

B  and  Belvedere  Tower  =125°     C  and  Belvedere  Tower  =  154°  35' 

Angle  i  C  P  =  121°  30' 
Hence  I  find 

Distance  from  i  to  P  =  483.8  feet  =  147.5  meters. 
Angle  C  i  P  =  24°  37'  35"  Angle  C  P  i  =  33°  52'  25" 

The  true  bearing  from  i  to  the  Belvedere  Tower  was  N.  68°  23'  28"  W.  Combining  this  with  the  angles 
given  above,  I  find  for  the  true  bearing  from  i  to  P,  S.  18°  20'  53"  E. 

The  instruments  were  used  in  the  open  air,  and  were  carried  back  into  the  store-house  whenever  the 
observers  were  done  with  them  for  the  time  being.  No  shelter  whatever  was  built  for  them. 


i  to  C  ==  316.2  feet  =  96.38  meters. 
C  to  P  =  236.4  feet  =  72.05  meters. 


III.— DESCRIPTION  OF  INSTRUMENTS. 

With  the  exception  of  the  chronometers,  the  instruments  employed  were  all  my  own  private  property. 
As  they  were  mostly  the  same  ones  that  I  used  at  Des  Moines,  in  observing  the  eclipse  of  August  7,  1869. 
all  of  which  are  fully  described  in  my  report  on  that  eclipse,  Appendix  II  to  the  Washington  Observations 
for  1867,  pp.  26-32,  it  will  only  be  necessary  to  give  a  list  of  them  here,  and  to  mention  such  changes  as 
were  made  in  them  for  the  present  eclipse. 

An  Achromatic   Telescope  of  43.58  inches  focal  length,  and  3.01  inches  clear  aperture,  made  by  Alvan 
Clark  &  Sons,  of  Cambridgeport,  Massachusetts.     This  instrument  is  provided  with  a  large  battery  of  eye- 
pieces, ranging  in  power  from  27.2  to  400  diameters.     It  is  equatorially  mounted  on  a  very  firm,  portable 
tripod  stand,  which  can  be  adjusted  to  any  latitude,  except  very  low  ones,  and  has  a  slow  motion  by  which 
it  may  be  moved  through  a  few  degrees  in  azimuth.     The  polar  and  declination  axes  are  both  provided  with 
clamp  screws ;  but  there  are  neither  divided  circles  nor  tangent  screws. 

The  finder  which  was  originally  furnished  with  this  telescope,  and  which  was  used  at  Des  Moines,  had 
a  clear  aperture  of  only  0.68  of  an  inch.     This  seemed  to  me  too  small ;  so  I  discarded  it,  and  substituted 
another  having  an  achromatic  object-glass  of  8.87  inches  focus  and  1.20  inches  clear  aperture.     It  is  pro- 
vided with  a  direct  eye-piece  magnifying  10.0  diameters,  and  a  diagonal  one  magnifying  6.3  diameters.     Each 
of  them  has  a  field  of  view  3°  15'  in  diameter.     The  pointing  apparatus  is  the  adjustable  needle-point  which 
was  used  at  Des  Moines. 

A  Single-Prism  Spectroscope,  having  the  following  optical  constants : 
Small  telescope: 

Focal  distance  of  object-glass     ...... 

Clear  aperture  of  object-glass      ..... 

Diameter  of  field  of  view  ....... 

Magnifying  power    ....... 

Collimating  lens  for  slit : 

Focal  distance          ........ 

Clear  aperture  ........ 


6.55  inches. 
0.86  inch. 

5°  33' 

5.71  diameters. 

6.52  inches. 
0.82  inch. 


REPORT  OF  PROFESSOR  HARKNESS. 


49 


Collimating  lens  for  scale: 

Focal  distance 

Clear  aperture 
Prism : 

Refracting  angle 

Minimum  deviation  of  line  D 

Refractive  index 

Density 


4.17  inches. 
0.82  inch. 

60°  8' 

47°  44' 
1.613 

3-S32 


Fig.  2. 


It  is  often  desirable  to  have  a  formula  which  will  enable  us  to  calculate  how  much  an  object  is  mag- 
nified when  seen  in  the  field  of  view  of  a  spectroscope  attached  to  a  telscope.  In 
order  to  obtain  such  a  formula,  let  us  consider  a  beam  of  perfectly  homogeneous  light 
— that  is,  light  of  but  a  single  wave  length — falling  upon  the  object-glass  of  a  telescope, 
a,  Figure  2.  It  will  be  brought  to  a  focus  at  b,  and  will  there  form  an  image  between 
the  jaws  of  the  slit  situated  at  that  point.  Then,  passing  through  the  collimating  lens 
f,  whose  principal  focus  is  at  />,  the  rays  composing  the  beam  will  be  rendered  parallel. 
Next,  falling  upon  the  prism  d,  the  beam  will  be  refracted  and  thrown  upon  the  lens  e, 
which  will  bring  it  to  a  focus  at  /,  where  a  second  image  will  be  formed.  This  image 
will  be  viewed  through  the  eye-lens  g. 
Now  let 

m  =  number  of  diameters  which  the  image  seen  in  the  field  of  view  of  the 

spectroscope-telescope  is  magnified. 
F  =  focal   length  of  object-glass  of  main  telescope — that  is,  of  the  lens  a  in 

Fig.  2. 
c  =  focal  length  of  the  collimator  of  the  spectroscope — that  is,  of  the  lens  c  in 

Fig.  2. 
f  —  focal    length  of  the  object-glass  of  the  spectroscope-telescope— that  is, 

of  the  lens  e  in  Fig.  2! 
/  =  focal  length  of  the  eye-piece  of  the  spectroscope-telescope — that  is,  of  the 

lens  g  in  Fig.  2. 
If  the  image  formed  at/ were  of  exactly  the  same  size  as  that  formed  at  b,  the  mag- 

f 

nifying  power  would  evidently  be  equal  to  — ;  and  the  actual  magnifying  power  will  be 


F 


f 


greater  or  less  than  — ,  according  as  the  image  at  /  is  larger  or  smaller  than  that  at  b- 

As  the  beam  of  light  is  supposed  to  contain  rays  of  only  a  single  wave  length,  the  prism  d  can  produce 
no  effect  upon  it  except  that  of  bending  it  out  of  a  straight  path,  and  the  size  of  the  image  at  b  must 
be  to  the  size  of  the  image  at  /  as  the  focal  length  of  the  lens  c  is  to  the  focal  length  of  the  lens  e.  The 
required  formula  will  therefore  be 

F       F1 

'"  =  7XT 

As  it  is  desirable  to  avoid  using  the  measured  focal  lengths  of  lenses  whenever, possible,  this  formula 
may  be  written 

F      F' 

m  =  —  x     , 

c        J 


where  —  is  the  magnifying  power  of  the  spectroscope-telescope — a  quantity  which  can  be  at  once  deter- 
mined by  means  of  a  Ramsden's  dynameter.  Applying  this  formula  to  the  case  of  the  spectroscope,  whose 
optical  constants  are  given  above,  used  in  connection  with  the  telescope  of  43.58  inches  focus,  we  find 

43-S8 

>«  = X  5.71  =38 

6.52 


50 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 

If,  instead  of  an  ordinary  spectroscope,  one  of  Mr.  Browning's  small  direct-vision 
instruments  is  employed,  the  formula  given  above  will  require  to  be  somewhat  modified. 
The  optical  arrangement  will  then  be  that  shown  in  Fig.  3.  The  light  falling  on  the  object. 
glass  a  will  be  brought  to  a  focus  at  />,  and  will  there  form  an  image  between  the  jaws  of 
the  slit  situated  at  that  point.  Then,  passing  through  the  lens  t,  whose  principal  focus  is  at 
A  the  rays  composing  the  beam  will  be  rendered  parallel,  and  after  traversing  the  direct- 
vision  prism  d  they  will  be  viewed  by  the  eye  of  the  observer.  Adopting  the  same  notation 
as  before,  in  this  case  we  shall  evidently  have 


An  Arago  Polariscope  of  double  rotation,  consisting  of  a  brass  tube  1.07  inches  in  diame- 
ter and  9.4  inches  long,  one  end  of  which  contains  two  plates  of  quartz,  each  cut  perpendicu- 
larly to  the  axis,  of  the  same  thickness,  and  standing  side  by  side,  but  one  of  them  possessing 
right-handed  rotation,  the  other  left-handed  rotation.  The  other  end  of  the  tube  contains  a 
double-image  prism,  and  a  convex  lens  of  9.0  inches  focal  length,  which  produces  distinct 
vision  of  the  compound  plate  of  quartz  to  an  eye  placed  at  the  double-image  prism.  This 
instrument  gives  images  of  complementary  colors  when  polarized  light  is  present. 

An  Arago  Polariscope,  consisting  of  a  plate  of  selenite,  and  a  double-image  prism,  giving 
images  of  complementary  colors  when  polarized  light  is  present.  This  instrument  is  fitted  to 
one  of  the  eye  pieces  of  the  43-inch  telescope. 

A  Savart  Polariscope,  consisting  of  a  plate  of  quartz  cut  obliquely  to  the  axis,  and  a 
plate  of  tourmaline,  giving  Savart's  bands  when  polarized  light  is  present.  This  instrument 
is  also  fitted  to  one  of  the  eye  pieces  of  the  43-inch  telescope. 
A  Sextant,  made  by  Stackpole  &  Brother,  of  New  York,  from  my  own  designs,  marked  No.  937,  of  six 
inches  radius,  divided  on  platinum,  and  reading  to  ten  seconds,  having  a  telescope  of  5.32  inches  focus  and 
0.89  inch  clear  aperture,  provided  with  eye-pieces  magnifying  respectively  2.75,  5.66,  and  8.88  diameters. 
Attached  to  the  index  bar  is  a  finding  level,  which  saves  much  time  and  trouble  in  picking  up  the  reflected 
image  of  an  object. 

Owing  to  my  severe  and  protracted  illness  in  Scotland,  I  have  not  had  time  to  make  any  investigation 
of  the  error  of  eccentricity  of  this  sextant  since  my  return.  In  reducing  the  observations,  I  have  therefore 
employed  the  errors  determined  in  1869,  which  are  given  in  the  following  table  ;  w  is  the  reading  on  the  arc 
and  E  the  corresponding  correction  for  eccentricity. 


a 

E 

<j 

E 

fj 

E 

o 

0.0 

50 

+  8.1 

too 

+  19.9 

10 

+    1.2 

60 

IO.2 

no 

22.6 

20 

2.6 

70 

12.5 

120 

25.3 

30 

4-3 

80 

14.9 

130 

28.0 

40 

+  6.1 

90 

+17.4 

I4O 

+30.8 

A  Mercurial  Artificial  Horizon ,  marked  Ha.  i,  having  a  folding  roof,  and  an  iron  trough  three  inches  wide 
by  five  inches  long.  A  very  careful  investigation  of  the  errors  of  this  horizon,  made  by  reflecting  the  pole 
star  from  it,  and  observing  the  reflected  image  with  the  mural  circle,  showed  that  the  maximum  error  which 
can  be  produced  in  the  mean  of  a  set  of  observed  double  altitudes  by  omitting  to  reverse  the  roof,  is 
only  o".24. 

A  Pocket  Sextant,  made  by  Stackpole  &  Brother,  of  New  York,  marked  No.  346,  having  an  arc  of  two 
and  a  quarter  inches  radius,  and  reading  to  single  minutes. 

A  Black  Glass  Artificial  Horizon,  four  inches  long  by  three  inches  wide,  provided  with  a  very  sensitive 
level  and  an  inclined  plane,  with  black  glass  surfaces,  which  can  be  set  on  the  horizon  for  the  purpose  of 
measuring  zenith  distances  ranging  between  seventy  and  one  hundred  and  thirty  degrees. 


REPORT  OF  PROFESSOR  HARKNESS. 


A  Prismatic  Compass,  having  colored  glasses  for  the  purpose  of  observing  the  sun,  and  a  needle  three 
inches  long,  carrying  a  metal  circle  three  inches  in  diameter,  divided  to  single  degrees. 

A  Small  Reflating  Level. 

Two  Pocket-Compasses. 

A  fifty-foot  C/iesterman's  Metallic  Tape- Measure,  which  had  been  carefully  tested  by  a  standard,  and  was 
found  to  be  too  long  in  the  proportion  of  100.134  to  100.000. 

A  Binocular  Field-Glass,  magnifying  5.50  diameters,  and  having  a  field  of  view  of  2°  50'. 

A  Pocket  Achromatic  Telescope,  having  an  object-glass  made  by  Alvan  Clark  &  Sons,  of  9.99  inches  focal 
length  and  1.09  inches  clear  aperture,  with  a  terrestrial  eye-piece  magnifying  19.2  diameters  and  a  field  of  view 
of  i°  48';  provided  with  a  screw  clip  for  holding  it  steadily  while  observing. 

A  set  of  three  Colored  Glasses,  mounted  in  a  gernmn-silver  frame,  for  the  pocket. 

A  Pocket  Aneroid  Barometer,  i  .9  inches  in  diameter,  made  by  L.  Casella,  of  London,  and  marked  No.  1 1 28- 
It  has  a  scale  extending  from  23  to  31  inches,  graduated  to  0.05  of  an  inch,  and  is  compensated  for  tem- 
perature. 

Two  Pocket  Thermometers. 

A  Rain  Gauge,  having  a  receiving  surface  2.788  inches  in  diameter,  and  a  glass  measure  for  the  same, 
holding  fifty  cubic  centimeters  and  graduated  to  half  a  cubic  centimeter — each  half  cubic  centimeter  being 
equal  to  0.005  °f  an  mcn  °f  ram- 

A  set  of  Drawing  Instruments. 

We  had  with  us,  for  the  use  of  the  party,  four  excellent  mean  time  box  chronometers,  made  by  T.  S.  & 
J.  D.  Negus,  of  New  York.  They  were  marked  numbers  1115,  1228,  1256,  and  1340. 

I  had  also  a  number  of  books  and  other  articles,  a  full  list  of  which  is  given  in  Addendum  C  to  this 
report. 

IV.— PROBABLE  ERROR  OF  OBSERVATIONS  MADE  WITH  A  SEXTANT. 

As  the  sextant  is  a  very  portable  and  convenient  instrument,  and  is  much  used  for  scientific  purposes, 
it  seems  worth  while  to  determine  carefully  what  degree  of  accuracy  may  be  expected  in  observations  made 
with  it.  For  that  purpose  I  have  collected  in  the  following  table  nearly  all  the  data  which  can  be  derived 
from  the  work  of  the  officers  of  this  Observatory  in  connection  with  the  total  solar  eclipses  of  August,  1869, 
and  December,  1870.  It  is  to  be  understood  that  each  set  of  altitudes  consists  of  six  readings,  the  object 
being  observed  in  a  mercurial  artificial  horizon,  with  a  sextant  whose  telescope  magnifies  about  nine  diameters, 
and  whose  vernier  reads  to  ten  seconds ;  and  further,  that  with  each  set  of  six  altitudes,  the  index  correc- 
tion has  been  determined  by  six  readings  made  for  that  purpose. 

TABLE  I. 


Observer. 

Station. 

Object  of 
Observations. 

Object 
Observed. 

No.  of  sets 
of  Altitudes. 

Probable 
Error  of  Time. 

Probable  Error 
of  Altitude. 

s. 

,, 

Harkness       .      . 

Des  Moines. 

^*~ 

Latitude 

Sun 

16 

±3.89 

Hall     .... 

Siberia     .... 

Latitude 

Sun 

13 

3.16 

Rogers 

Siberia     .... 

Latitude 

Sun 

6 

2-47 

Harkness 

Syracuse. 

Latitude 

Sun 

ii 

2.98 

Hall     .... 

Syracuse  and  Malta 

Latitude 

Sun 

ii 

3.12 

Harkness 

Des  Moines. 

Time 

Sun 

20 

±0.145 

1.63 

Harkness 

Syracuse. 

Time       .     . 

Sun 

38 

.321 

2.59 

Hall     .... 

Syracuse  and  Malta 

Time       .     . 

Sun 

40 

.381 

3.05 

Harkness 

Des  Moines. 

Latitude        .      Polaris 

3 

6.85 

Harkness 

Syracuse. 

Latitude       .      Polaris 

6 

8.29 

Hall     .... 

Syracuse. 

Latitude 

Polaris 

3 

3-45 

In  the  case  of  the  time  observations  given  in  the  above  table,  the  average  azimuths  were  as  follows, 
namely:  at  Des  Moines,  90°;  at  Syracuse,  42°  27';  at  Syracuse  and  Malta,  42°. 


52  OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 

The  observations  of  the  sun  give  the  following  results:  57  sets  of  altitudes,  observed  to  determine  lati- 
tude, give  for  the  probable  error  of  the  mean  of  a  single  set  zt  3".25;  and  98  sets  of  altitudes,  observed  to 
determine  local  time,  give  for  the  probable  error  of  the  mean  of  a  single  set  ±  2". 58.  The  arithmetical 
mean  of  these  two  values  is  ±  2". 92.  I  therefore  adopt  as  the  probable  error  of  the  mean  of  a  set  of  six 
altitudes  of  the  sun  ±  3".oo  —  a  result  which  rests  on  no  less  than  930  observed  altitudes. 

The  number  of  observations  on  stars,  contained  in  Table  I,  is  not  sufficiently  great  to  render  it  possible 
to  determine  a  reliable  probable  error  from  them,  but  it  is  evident  that  the  probable  error  of  an  observation 
of  a  star  is  greater  than  that  of  an  observation  of  the  sun. 

To  an  officer  in  the  field  desirous  of  determining  local  time,  it  is  a  matter  of  importance  to  know  pre- 
cisely at  what  hour  angle  it  will  be  most  advantageous  to  observe.  I  have  therefore  constructed  the  follow- 
ing table,  which  will  enable  a  person  in  any  latitude,  and  with  the  sun  at  any  declination,  to  ascertain  almost 
at  a  glance  the  altitude,  azimuth,  and  hour  angle  when  the  sun  is  in  the  most  favorable  position  for  time 
observations.  The  numerical  computations  for  the  table  have  been  made  by  Mr.  Ormond  Stone,  and  in 
constructing  it  I  have  assumed  that  the  altitudes  must  be  confined  between  sixteen  and  seventy  degrees, 
these  being  about  the  limits  of  convenient  observation  with  a  sextant.  <5  is  the  sun's  declination. 


REPORT  OF  PROFESSOR  HARKNESS. 


53 


•apmpirj 

O       i/»      O       ""'      O       m      O       ""i      O       m      C       io      O       "">      O       >r>      O       ""i 
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54 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


If  we  let 

d  J  =  probable  error  of  an  observed  zenith  distance,  expressed  in  seconds  of  arc, 
dt  =  probable  error  of  the  corresponding  hour  angle,  expressed  in  seconds  ot  time, 
<p  =  latitude  of  the  place  of  observation, 
A  =  azimuth  of  the  sun  at  the  time  of  observation, 
then  we  shall  have 


dt-. 


15  cos  <f  .  sin  A 


by  means  of  which  formula  I  have  computed  Table  III.     The  azimuths  have  been  taken  from  Table  II, 
and  </C  has  been  assumed  equal  to 


3".oo. 


TABLE  III. — Probable  Error  of  a  Chronometer  Correction  determined 'from  the  mean  of  Six  Double  Altitudes  of  the 
Sun,  observed,  when  in  the  most  favorable  position,  by  means  of  a  Sex/an/. 


Latitude. 

Latitude  and  Declination  of  the  same  name. 

Declination, 
o° 

Latitude  and  Declination  of  different  name. 

Latitude. 

il^5 

«.«r 

<S=i5° 

<J=  10° 

*  =  »• 

«  =  S° 

(5  =  10° 

(!      15" 

<J  =  2O° 

0  =  23°, 

0 

s. 

s. 

s. 

s. 

s. 

s. 

s. 

s. 

s. 

S. 

s. 

0 

0 

±0.22 

±0.21 

±0.21 

±0.20 

±0.20 

±0.20 

±0.20 

±0.20 

±O.2I 

±O.2I 

±0.22 

0 

5 

.22 

.21 

.21 

.20 

.20 

.20 

.20 

.21 

.21 

.22 

.22 

5 

10 

.22 

.21 

.21 

.20 

.20 

.20 

.21 

.21 

.21 

.22 

•23 

10 

15 

.22 

.21 

.21 

.21 

.21 

.21 

.21 

.21 

.22 

•23 

.24 

15 

20 

.22 

.21 

.21 

.21 

.21 

.21 

.22 

.22 

•23 

.24 

•25 

20 

25 

.22 

.22 

.22 

.22 

.22 

.22 

•23 

•23 

.24 

.26 

•27 

25 

30 

•23 

.23 

.23 

•23 

•23 

•23 

.24 

•25 

.26 

.28 

•3° 

30 

35 

•24 

•24 

.24 

•24 

•24 

•25 

.26 

•27 

•29 

•32 

•35 

35 

40 

.26 

.26 

.26 

.26 

.26 

.27 

.28 

.30 

.32 

•37 

•42 

40 

45 

.28 

.28 

.28 

.28 

.29 

•30 

•31 

•34 

•38 

.46 

0.58 

4? 

50 

•31 

•31 

•31 

•31 

•32 

•  33 

•36 

.40 

.48 

0.81 

1.94 

50 

55 

•35 

•35 

•  35 

•  35 

•36 

•  38 

.42 

•  5i 

0-73 

55 

60 

.40 

.40 

.40 

.40 

.42 

.46 

•  54 

0.78 

60 

65 

•  47 

•  47 

•  47 

.48 

•52 

.60 

0.85 

f'5 

70 

•  58 

•  58 

•  58 

.61 

O.6g 

0-95 

70 

75 

0-77 

0.77 

0.77 

0.83 

I.  II 

75 

80 

I.  IS 

I-I5 

1.15 

1.42 

So 

85 

2.30 

2.30 

2-34 

85 

Putting 

r  =  probable  error  of  a  single  set  of  observations, 
r0  =  probable  error  of  arithmetical  mean  of  m  sets  of  observations, 
c  =  constant  error  affecting  each  set  of  observations, 
pm  =  weight  of  the  arithmetical  mean  of  m  sets  of  observations, 


we  have 


r.  =• 


It  is  usual  to  assume  /,„  proportional  to  V ' m;  but,  inasmuch  as  experience  shows  that  in  the  case  of 
every  instrument  there  is  a  limit  beyond  which  increasing  the  number  of  observations  adds  almost  nothing 
to  the  accuracy  of  the  final  result,  I  have  preferred  to  follow  the  principles  laid  down  by  Dr.  B.  A.  Gould 


REPORT  OF  PROFESSOR  HARKNESS. 


55 


in  his  discussion  of  the  weights  and  mean  errors  of  the  observations  of  Mars  and  Venus  made  during  the 
years  i849~'52,  and  employed  to  determine  the  solar  parallax.*    In  accordance  with  these  principles,  putting 


we  find 


m  +  b 


l>  depends  solely  upon  the  quality  of  the  observations  employed,  and  increases  in  the  ratio  of  their 
accuracy,  so  that  IP  sets  of  observations  are  worth  b  times  as  much  as  one  set,  but  no  finite  number  of  sets  can 
ever  be  worth  b  +  i  times  as  much  as  one  set.  The  numerical  value  of  b  is  arbitrary.  For  sextant  work 
the  observations  which  I  have  been  able  to  examine  seem  to  indicate  as  the  most  probable  value,  b  =  3. 
That  I  have  adopted,  and  by  substituting  it  in  the  formula  for //»,  given  above,  I  have  computed  Table  IV. 

TABLE  IV. —  Weights  as  Functions  of  the  Number  of  Observations. 


No. 

Weight. 

No. 

Weight. 

No. 

Weight. 

No. 

Weight. 

No. 

Weight. 

i 

I.  00 

6 

2.67 

12 

3.20 

25 

3-57 

50 

3-77 

2 

i.  60 

7 

2.80 

14 

3-29 

30 

3-64 

60 

3-8i 

3 

2.OO 

8 

2.91 

16 

3-37 

35 

3.68 

75 

3.85 

4 

2.  2Q 

9 

3.00 

18 

3-43 

40 

3-72 

IOO 

3-88 

5 

2.50 

TO 

3-oS 

20 

3.48 

45 

3-75 

IOOO 

3-99 

By  means  of  the  weights  contained  in  Table  IV,  I  have  computed  Table  V,  which,  with  the  argument 
"  Probable  error  of  a  single  set  of  observations"  gives  the  probable  error  of  the  arithmetical  mean  of  any 
number  of  sets  of  observations  not  greater  than  100.  The  figures  placed  at  the  head  of  each  column  indi- 
cate the  number  of  sets  of  observations  to  the  mean  of  which  the  probable  errors  contained  in  that  column 
apply.  The  table  is  used  by  entering  the  column  headed  "i"  with  the  known  probable  error  of  a  single  set 
of  observations;  then,  on  the  same  line  with  this  known  probable  error,  in  the  column  headed  "  2"  will  be 
found  the  probable  error  of  the  arithmetical  mean  of  two  sets  of  observations ;  in  the  column  headed  "  3," 
the  probable  error  of  the  arithmetical  mean  of  three  sets  of  observations ;  and  so  on  for  each  of  the  other 
columns. 


*  United  States  Naval  Astronomical  Expedition  to  the  Southern  Hemisphere,  Vol.  Ill,  page  cclii. 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


TABLE  V.  —  Probable  Error  of  the  Mean  of  several  sets  of  Sextant  Observations,  i-x 

number  of  sets,  there  being  Six  Observed  Altitudes  in  eacli  set. 


us  a  Function  of  the 


I 

2 

3 

4 

5 

6 

7 

8 

9 

10 

20 

50 

too 

,, 

,, 

,, 

It 

„ 

,, 

„ 

„ 

„ 

,, 

„ 

„ 

,, 

±3.00 

±1.87 

±1.50 

±1.31 

±1.20 

±1.12 

±1.07 

±1.03 

±1.00 

±0.97 

±0.86 

±0.80 

±0.77 

s. 

S. 

s. 

s. 

s. 

S. 

s. 

s. 

s. 

s. 

s. 

s. 

s. 

O.2O 

O.I2 

O.JO 

0.09 

0.08 

0.08 

0.07 

0.07 

0.07 

0.06 

0.06 

0.05 

0.05 

.22 

.14 

.11 

.  IO 

.09 

.08 

.08 

.08 

•07 

.07 

.06 

.06 

.06 

.24 

•15 

.12 

.10 

.10 

.09 

.09 

.08 

.08 

.08 

.07 

.06 

.06 

.26 

.16 

•13 

.11 

.10 

.  IO 

.09 

.09 

.09 

.08 

.07 

.07 

•  07 

.28 

.18 

.14 

.12 

.11 

.10 

.10 

.10 

.09 

.09 

.08 

.07 

.07 

.30 

.19 

•15 

•13 

.12 

.  II 

.11 

.10 

.10 

.10 

.09 

.08 

.08 

•32 

.20 

.16 

.14 

•13 

.12 

.11 

.11 

.11 

.10 

.09 

.08 

.08 

•  34 

.21 

•17 

•15 

.14 

•13 

.12 

.  12 

.11 

.11 

.10 

.09 

.09 

.36 

.22 

.18 

.16 

.14 

•13 

•13 

.12 

.12 

.12 

.10 

.10 

.09 

-38 

.24 

.19 

•17 

•15 

.14 

.14 

•13 

•13 

.12 

.11 

.  IO 

.10 

.40 

•25 

.20 

•17 

.16 

•15 

•14 

.14 

•13 

•13 

.12 

.11 

.10 

•45 

.28 

.22 

.20 

.18 

•17 

.16 

•15 

•15 

•15 

•13 

.12 

.  12 

.50 

•31 

•25 

.22 

.20 

.19 

.18 

•17 

•17 

.16 

•14 

•13 

•13 

.60 

•38 

•3° 

.26 

.24 

.22 

.21 

.21 

.20 

.19 

•17 

.16 

•15 

0.80 

•50 

.40 

•35 

•32 

.30 

.29 

•27 

.27 

.26 

•23 

.21 

.21 

I.OO 

.62 

•50 

•  44 

.40 

•  37 

•36 

•  34 

•  33 

•  32 

.29 

•27 

.26 

1.50 

0.94 

0.75 

.66 

.60 

•  56 

•  54 

.52 

•  50 

•49 

•  43 

.40 

•39 

2.OO 

1.25 

I.OO 

0.87 

0.80 

•  75 

•  71 

.69 

.67 

•  65 

•  57 

•  53 

•  5  = 

2.50 

1.56 

1-25 

1.09 

I.OO 

0.94 

0.89 

0.86 

0.83 

o.8r 

0.72 

0.66 

0.64 

In  order  to  meet  cases  where  more  or  less  than  six  altitudes  have  been  observed  in  each  set,  I  have 
made  use  of  the  weights  contained  in  Table  IV  to  compute  Table  VI,  which,  with  the  argument  "  Probable 
error  of  the  mean  of  six  altitudes"  gives  the  probable  error  of  the  mean  of  various  numbers  of  altitudes, 
ranging  between  i  and  20.  The  arrangement  of  this  table  is  similar  to  that  of  Table  V. 


REPORT  OF  PROFESSOR  IIARKNESS. 


57 


TABLE  VI. — Probable  Error  of  the  Mean  of  a  set  of  Sextant  Observations,  expressed  as  a  function  of  the 

number  of  Observed  Altitudes. 


6 

I 

2 

3 

4 

5 

8 

10 

12 

M 

16 

18 

20 

±  3-00 

±  S.oi 

±  5-01 

±  3-99 

±  3-48 

±  3.21 

±  2.75 

±  2.60 

±  2.50 

±  2.43 

±  2.37 

±  2-33 

±  2.30 

s. 

s. 

S. 

s. 

s. 

s. 

s. 

s. 

S. 

s. 

s. 

s. 

S. 

0.20 

o.53 

o.33 

0.27 

0.23 

0.21 

o.iS 

0.17 

0.17 

0.16 

0.16 

0.16 

0.15 

.22 

•59 

•37 

.29 

.26 

.24 

.20 

.19 

.18 

.18 

•i? 

•  17 

.17 

.24 

.64 

.40 

•  32 

.28 

.26 

.22 

.21 

.20 

.19 

.19 

.19 

.18 

.26 

.69 

•43 

•35 

•  30 

.28 

•24 

•23 

.22 

.21 

.21 

.20 

.20 

.28 

•  75 

•47 

•37 

•  32 

•  30. 

.26 

.24 

•23 

•23 

.22 

.22 

.21 

•30 

.80 

•50 

.40 

•35 

•  32 

•  27 

.26 

•25 

.24 

.24 

.23 

•23 

.32 

•  85 

•53 

•  43 

•  37 

•34 

.29 

.28 

•27 

.26 

•25 

•25 

•25 

•34 

.91 

•57 

•  45 

•39 

•  36 

•31 

.29 

.28 

.28 

•27 

.26 

.26 

•36 

0.96 

.60 

.48 

.42 

•39 

•33 

•31 

•  30 

.29 

.28 

.28 

.28 

•38 

I.OI 

•63 

•  Si 

•44 

•  41 

•35 

•  33 

•  32 

•31 

•30 

.30 

•29 

.40 

.07 

.67 

•53 

.46 

•43 

•  37 

•  35 

•33 

.32 

•32 

•  31 

•31 

•  45 

.20 

•75 

.60 

•52 

.48 

•  4i 

•39 

•38 

•36 

•36 

•35 

•  34 

.50 

•33 

0.84 

.66 

•  58 

•54 

.46 

•43 

•42 

.41 

.40 

•39 

•38 

.60 

i.  60 

I.OO 

0.80 

.70 

.64 

•  55 

•  52 

•  50 

.49 

•47 

•47 

.46 

0.80 

2.14 

•34 

1.  06 

o-93 

0.86 

•73 

.69 

.67 

•  65 

•  63 

.62 

.61 

I.  00 

2.67 

1.67 

i-33 

1.16 

1.07 

0.92 

0.87 

0.83 

0.81 

0-79 

0.78 

0.77 

1.50 

4.00 

2.50 

2.OO 

i-74 

i.  60 

1-37 

1.30 

1.25 

1.22 

1.19 

1.17 

I-I5 

2.00 

5-34 

3-34 

2.66 

2.32 

2.14 

1.83 

i-73 

1.67 

1.62 

•58 

•56 

•  53 

2.50 

6.68 

4.18 

3-32 

2.90 

2.68 

2.29 

2.16 

2.08 

2.03 

1.98 

1.94 

1 

1.92 

Of  course  these  tables  apply  only  to  the  probable  accidental  errors,  and  afford  no  clew  whatever  to  the 
constant  errors.  In  order  to  get  rid  of  the  latter  a  special  investigation  must  be  made  for  the  instrument 
employed,  or  else  care  must  be  taken  to  make  all  the  observations  in  pairs,  upon  objects  at  about  equal 
altitudes  on  each  side  of  the  zenith.  Table  VI  shows  that  almost  nothing  is  gained  by  observing  more  than 
six  altitudes  in  each  set,  and  Table  V  shows  that  there  is  very  little  use  in  making  more  than  ten  sets  of 
observations  for  any  one  object.  That  is,  supposing  the  constant  errors  to  be  entirely  eliminated,  a  latitude 
depending  upon  the  mean  of  ten  good  sets  of  meridian  altitudes  is  as  trustworthy  as  any  that  can  be  found 
from  observations  with  a  sextant ;  and  a  chronometer  correction  depending  upon  the  mean  of  three  sets  of 
altitudes  observed  to  the  east,  and  an  equal  number  observed  to  the  west,  of  the  meridian,  the  sun  being  at 
about  the  same  altitude  in  each  case,  is  as  reliable  as  any  that  can  be  obtained  by  means  of  a  sextant. 

V.— GENERAL  REMARKS  ON  THE  OBSERVATIONS  FOR  TIME  AND  LATITUDE. 

The  observations  for  time  and  latitude  were  all  made  by  me,  assisted  usually  by  Professor  Eastman,  who 
noted  the  time  at  a  given  signal,  and  then  recorded  the  observation.  On  two  or  three  occasions  I  was 
assisted  by  Professor  Hall,  and  again  by  Captain  G.  L.  Tupman.  In  the  first  observation  that  I  made  at 
Syracuse  I  attempted  to  take  up  the  beat  of  the  chronometer  and  note  the  times  myself,  but  I  soon  aban- 
doned that  plan  because,  owing  to  noise  and  other  disturbing  influences,  it  did  not  seem  either  so  accurate 
or  so  convenient  as  to  have  the  times  noted  by  an  assistant.  The  instruments  employed  were  the  sextant 
Suickpole  and  Brother,  No.  937,  with  a  magnifying  power  of  8.88  diameters  on  its  telescope ;  the  mercurial 
artificial  horizon  Ha.  i;  and  the  mean  time  box  chronometer  T.  S.  and  J.  D.  Negus,  No.  1115.  When 
observing  the  sun,  half  the  altitudes  were  always  measured  on  one  limb,  with  the  roof  of  the  artificial  hori- 
zon in  one  position,  and  the  other  half  of  the  altitudes  were  measured  on  the  other  limb,  with  the  roof  of  the 
horizon  reversed.  When  observing  stars  half  the  altitudes  were  measured  with  the  roof  in  one  position, 
and  the  other  half  with  it  reversed.  In  the  day-time  the  index  correction  of  the  sextant  was  determined  by 
measuring  the  diameter  of  the  sun  both  on  and  off  the  arc ;  at  night  it  was  determined  by  observing  the 
contact  of  the  direct  and  reflected  image  of  a  star. 
8 


58  OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 

Throughout  this  report  civil  dates  are  employed.  The  refractions  have  been  computed  by  means  of 
Bessel's  formula,  using  the  tables  given  in  the  Appendix  to  the  Washington  Observations  for  1845.  For 
latitude  observations  the  tabular  part  of  the  reductions  to  the  meridian  has  been  taken  from  Loomis's  Prac- 
tical Astronomy.  All  astronomical  data  required  in  the  reductions  have  been  taken  from  the  American 
Ephemeris  and  Nautical  Almanac.  For  further  details  as  to  the  mode  of  observing,  the  formulae  employed 
in  the  reductions,  &c.,  reference  may  be  made  to  my  Report  on  the  Total  Solar  Eclipse  of  August  7,  1869.* 

VI.— OBSERVATIONS  FOR  TIME. 

The  observations  for  time  are  given  in  detail  in  Addendum  A  to  this  report,  but  for  convenience 
of  reference  the  following  abstract  of  them  is  inserted  here.  The  first  column  of  the  table  contains 
the  dates;  the  second  column  contains  the  corrections  to  the  chronometer  derived  from  the  individual 
sets  of  observations  made  in  the  forenoon;  the  third  column  contains  the  corrections  derived  from  the  sets 
of  observations  made  in  the  afternoon ;  the  fourth  column  contains  for  each  day  the  mean  of  the  corrections 
given  by  the  forenoon  observations;  the  fifth  column  contains  for  each  day  the  mean  of  the  corrections 
given  by  the  afternoon  observations ;  the  sixth  column  contains  for  each  day  the  mean  of  the  numbers 
given  in  the  fourth  and  fifth  columns,  which  is  taken  to  be  the  correction  to  the  chronometer  at  noon;  the 
seventh  column  contains  the  resulting  daily  rates.  The  observations  on  the  morning  of  December  13  were 
made  at  the  Prima  Porta  Terra,  os.i3  east  of  the  Stone  Gun-Platform,  but  in  computing  the  correction  to 
the  chronometer  at  noon  of  that  day  the  necessary  allowance  has  been  made  to  reduce  them  to  the  Stone 
Gun-Platform. 

*  Appendix  II  to  the  Washington  Observations  for  1867,  pp.  33-40. 


REPORT  OF  PROFESSOR  HARKNESS. 

Chronometer  T.  S.    &  jf.  D.  Negus  No.   1115  slou<  of  Mean  Time  at  the  Stone  Gun- 
Platform,  Syracuse,  by  observation. 


59 


Date. 

A.M. 

P.  M. 

Means. 

Correction 
at  Noon. 

Daily  Rate. 

A.  M. 

P.  M. 

1870. 

h.  m.      s. 

s.                  s.                   s. 

h.  m.       s. 

s. 

December    13 

+      I      2      42.9 

42.9 

43-8 

43.1 

43.47* 

43.00 

+   I     2     43.17 

43-7 

+     0.70 

M 

42.8 

44.2 

43-9 

44-3           43-77 

43-97 

43-87 

44.6 

43-4 

0-49 

15 

43-8             44-7 

45-1              43.8           44.50 

44-23 

44.36 

44.6     ;         44.2 

0.32 

16 

43-8 

44-2 

45-3 

44-3 

44.80 

44-57 

44.68 

•45-3 

45-2 

O.2I 

19 

46.  1 

44.4 

45-8 

44-5 

46.07 

44-53 

45.30 

46-3 

44-7 

+       0.12 

21 

45-4 

44-9 

46.7 

44-5 

46.37 

44.70 

45-54 

47.0 

44-7 

22 

45.6 

45-3 

45.13 

+    I      2      45.14 

+     I     2     44-5 

*o".i3  to  the  east  of  Stone  Gun-Platform. 

At  the  time  of  the  eclipse,  on  December  22,  I  have  taken  this  chronometer  to  be  ih  2m  45S.7  slow 
of  mean  time  at  the  Stone  Gun-Platform. 

The  following  table  contains  all  the  chronometer  comparisons  made  while  we  were  at  Syracuse,  and  I 
desire  to  call  particular  attention  to  the  remarkably  good  running  of  the  chronometers  No.  1115  and  No. 
1256.  Such  a  result  shows  the  great  degree  of  perfection  to  which  the  manufacture  of  these  instruments 
has  been  carried. 

The  chronometer  French  No.  21778  belonged  to  Mr.  Brothers,  ot  the  English  Expedition,  and  was 
used  by  him  in  timing  the  exposures  of  his  photographic  plates.  It  had  a  losing  rate  of  about  six  seconds 
per  day. 


6o 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 
Chronometer  Comparisons  made  at  Syracuse. 


Date. 

Negus  1115. 

Negus  1228. 

Negus  1340. 

Negus  1256. 

1870. 

h.    m.    s. 

h.    m.       s. 

h.    m.        s. 

h.    m.       s. 

December  13 

3     16    o 

3     19     22.  o 

3     17     39-4 

14 

9     21     o 

9     24     23.2 

9    22     39.5 

14 

2     50    o 

2     53     24.2 

2     51     39.7 

15 

8     31     o 

8     34    25.7 

8     32     39.7 

15 

2      23      O 

2      26      26.O 

2     24     39.7 

16 

880 

8     ii     28.2 

8      9     39-7 

16 

2       28      0 

2      31      28.2 

2     29     39.7 

17 

II     18     o 

ii     20      5.7 

II       21       3O.O 

ii     19     39.8 

19 

u     15    o 

ii     17      6.3 

II     IS     33.2 

II     16     40.0 

21 

II       28      0 

ii     30      6.5. 

II   31   37.5 

II     29     40  .  I 

22 

920 

9      4      7-2 

9       5     39-2 

9      3     40.2 

22 

2       30      O 

2     32       7.2 

2     33     39-8 

2  ,  31     40.4 

French  21778. 

• 

h.     m.       s. 

22 

8     57     o 

8     54     47.1 

22 

2     53     o 

2     50    45-5 

• 

VII.— OBSERVATIONS  FOR  LATITUDE. 

The  observations  for  latitude  are  given  in  detail  in  Addendum  B  to  this  report;  but  for  convenience  of 
reference  the  following  abstract  of  them  is  inserted  here. 

Abstract  of  Results  of  Observations  for  Latitude  of  the  Stone  Gun-Platform  at  Syracuse. 


Date. 

Object. 

Latitude. 

1870. 

Sun            

-4-77    7    6^ 

14 
14 
16 

Polaris      
Polaris      
Sun      

66 

47 
56 

16 

cS 

16 

16 

17 

Polaris      
Polaris      

37 
43 
63 

17 

Sun      

53 

18 

Sun      .           .... 

62 

18 

Sun      

63 

Sun      

52 

TO 

Sun      

57 

54 

19 

21 

Polaris      

6? 

63 

21 

Sun      

64 

REPORT  OF  PROFESSOR  HARKNESS.  6  I 

Taking  separately  the  mean  of  the  latitudes  resulting  from  observations  on  the  sun,  and  the  mean  of 

the  latitudes  resulting  from  observations  on  Polaris,  I  find 

°      i         n  a 

From  the  Sun  +37     3     59-4  ±  °-9° 

From  Polaris 52.3  ±  3.38 


Mean +  37     3     55-9 


As  the  value  from  the  sun,  and  that  from  Polaris,  differ  from  each  other  by  more  than  the  square  root 
of  the  sum  of  the  squares  of  their  probable  errors,  I  infer  that  they  are  affected  by  a  small  constant  error, 
and  I  therefore  take  their  mean  as  the  value  of  the  latitude  to  be  derived  from  my  observations. 

Professor  Hall's  observations  at  Syracuse,  reduced  by  himself,  give  for  the  value  of  the  latitude 

o        /       // 

From  the  Sun         ...  .  +    37     3     59-7 

From  Polaris  .........  35-° 


Mean +    37     3     47-3 


My  result  for  latitude  depends  on  one  hundred  and  two  observed  altitudes ;  Professor  Hall's  on  sixty- 
four  observed  altitudes.  Giving  each  determination  weight  in  proportion  to  the  number  of  altitudes  on 
which  it  depends,  I  get  finally  for  the  latitude  of  the  Stone  Gun-Platform 

+  37°3'S2"-6  ±2".98 
and  that  value  I  adopt. 


VIII.— TRIANGULATION  AT  SYRACUSE. 

In  order  to  connect  our  observing  station  at  the  Stone  Gun-Platform  with  the  various  conspicuous  land- 
marks in  the  city  of  Syracuse,  it  was  necessary  to  make  a  small  triangulation. 

On  passing  out  of  the  city  toward  the  main-land,  about  one-eighth  of  a  mile  (200  meters)  beyond  the 
fortifications,  we  come  to  an  open  circular  space  perhaps  three  hundred  feet  (98  meters)  in  diameter.  From 

Fig.  4. 


this  circular  space  four  roads  radiate.  That  directed  N.  82°  W.  (true)  leads  to  Avola  and  Noto.  Travel- 
ing along  it  for  a  little  more  than  half  a  mile  (860  meters)  we  come  to  a  small  stream,  crossed  by  a 
substantial  stone  bridge  of  three  arches.  Continuing  in  the  same  direction  about  seven-eighths  of  a  mile 
(1,390  meters)  further  we  come  to  another  fine  stone  bridge,  which,  in  this  case,  consists  of  a  single  arch 
spanning  the  Anapus  River.  The  land  between  these  two  bridges  is  low  and  marshy,  and  the  road  is  an 
artificial  causeway  protected  throughout  nearly  its  whole  length  by  a  stone  wall  on  its  eastern  side.  This 
wall  rises  about  three  feet  above  the  surface  of  the  road,  and  its  top  is  covered  with  heavy  coping-stones. 
On  these  coping-stones  Professor  Hall  and  I  measured  the  base-line  which  is  shown  on  a  scale  of  i  to 
10,000  in  Figure  4.  The  causeway  was  not  quite  straight,  which  obliged  us  to  measure  the  base  in  four 
sections;  the  northern  terminus,  5,  Fig.  4,  being  directly  above  the  key-stone  in  the  east  face  of  the  central 
arch  of  the  three-arched  bridge ;  and  the  southern  terminus,  6,  Fig.  4,  being  directly  above  the  key-stone  in 
the  east  face  of  the  arch  over  the  Anapus  River.  The  measurements  were  made  on  December  20,  with  my 
Chesterman's  metallic  tape-line,  which  is  too  long  in  the  proportion  of  100.134  to  100.000.  This  explains 


62 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


the  origin  of  the  column,  "Corrected  distances,"  in  the  following  table  giving  the  details  of  the  measure- 
ment of  the  base-line: 


Stations. 

Measured  Distances 
in  Feet. 

Corrected  Distances 
in  Feet. 

Corrected  Distances 
in  Meters. 

From  5  to  e   . 
From  e  to  f  . 
From  f  to  g  . 
From  g  to  6  . 

5«/   .     •     •     • 

*fe   •    •    •    • 
fgt>  .... 

372.58 
1850.00 
2150.00 
187.75 

372.08 
1847.52 
2147.12 
187.50 

"3-41 
563.15 
654-47 
57-15 

Observed  Angles. 

166      5 
170    30 
144     56 

The  following  table  gives  the  results  of  the  successive  steps  in  reducing  this  base  to  a  straight  line  : 


Stations. 

Angles. 

Distances  in 
Feet. 

Distances  in 
Meters. 

S'f     

166      5       o 

From  5  to  /    . 

2210.51 

673.79 

S/f    

168     10    47 

From  5  to  g    , 

4334-28 

1321.14 

5  g  6     

150    55    48 

From  5  to  6     . 

4499.09 

f37L38 

On  December  20  and  21,  Professor  Hall  and  I  executed,  upon  this  base,  the  triangulation  shown  in 
Fig.  5,  which  is  drawn  on  a  scale  of  i  to  15,000.  The  different  stations  are  designated  in  the  figure  by 
numerals,  as  follows : 

1  is  the  Stone  Gun-Platform,  the  position  of  which  is  described  on  page  48. 

2  is  the  Light-House  on  Maniace  Castle. 

3  is  the  highest  point  in  the  center  of  the  facade  of  the  cathedral,  which  in  ancient  times  was  the  Tem- 

ple of  Minerva. 

4  is  the  cupola  of  the  Chiesa  del  Collegio. 

5  is  the  north  end  of  the  base,  which  is  directly  above  the  key-stone  in  the  east  face  of  the  central 

arch  of  the  three-arched  bridge. 

6  is  the  south  end  of  the  base,  which  is  directly  above  the  key-stone  in  the  east  face  of  the  arch  of  the 

bridge  over  the  Anapus  River. 

7  is  the  Belvedere  Tower,  which  is  not  shown  in  the  figure. 


REPORT  UF  PROFESSOR  HARKNESS. 


Fig-  5- 


Scale  cfJIalf  a  Mile. 
o.o         o.z         o.2        0.3         0.4.         0.5 


64  OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 

By  means  of  my  pocket  sextant,  Stackpole  &  Brother,  No.  346,  the  following  angles  were  measured 


Angles  at  I. 

Angles  at  5. 

Angles  at  6. 

o                 / 

6  i  5  =  23      9 

152  =  39     ii 

i  62  =  31     14 

3  i  5  =  98     24 

i  5  3  =  22     45 

I  63   =    15         2 

4  i  5  =  95     13 

i  54  =  19     25 

164=12      o 

5  I  7  =  25     24 

3  5  2  =  16     16 

3  6  2  =  16     12 

6  i  7  =  48     32 

4  5  2  =  19     40 

462  =   19      12 

453=     3     24 

463=3         2 

2  5  6  =  92     20 

5  6  2  =  56     40 

5  6  I  =  25     27 

5  6  3  =  40     29 

By  correcting  these  angles  in  accordance  with  the  method  of  least  squares,  and  then  converting  them 
into  directions,  the  corrected  directions  given  in  the  third  column  of  the  subjoined  table  were  obtained. 


Table  of  Corrected  and  Adjusted  Directions. 


Station. 

Object. 

Corrected 
Direction. 

Correction  by 
Adjustment. 

Adjusted 
Direction. 

North  Base    .... 

Stone  Gun-Platform 

o      o.o 

+0.48 

0                '               " 

o      o    29 

Cupola  of  Chiesa  del  Collegio 

19     25-5 

-   -25 

19    25    15 

Cathedral       

22      48.5 

+     .10 

22      48      36 

39       7.o 

39      7      o 

131     27.0 

-    .33 

131     26    40 

South  Base    .... 

North  Base    

o       o.o 

+    .38 

O        O      22 

Stone  Gun-Platform 

25     26.9 

-    .61 

25    26     17 

Cupola  of  Chiesa  del  Collegio 

37     27.4 

+   .36 

37     27     46 

Cathedral       

40     28.9 

-    .  12 

40     28     47 

Light-House       

56     40.3 

56    40     18 

Cathedral       

o      o.o 

—    .02 

359     59     59 

Cupola  of  Chiesa  del  Collegio 

3     ii.  o 

+    .04 

3112 

South  Base    

75     15.5 

+     -29 

75     15     47 

North  Base    

98     24  .  o 

—  0.31 

98     23     41 

Belvedere  Tower      .... 

123     47.8 

123     47     48 

In  order  to  facilitate  the  adjustment  of  this  triangulation  by  the  method  of  least  squares,  I  have  adopted 
the  following  notation :  Retaining  the  numerical  designation  of  the  stations  already  given,  two  numbers 
written  one  above  the  other  indicate  the  direction  from  the  station  corresponding  to  the  lower  number  to 
that  corresponding  to  the  upper  number;  thus,  \  would  indicate  the  direction  from  5  to  i,  and  f  would  in- 
dicate the  direction  from  5  to  6.  As  the  difference  of  two  directions  is  an  angle,  — \  +  \  would  indicate  the 
angle  156.  If  the  numbers  are  inclosed  between  brackets  they  indicate  a  correction;  thus,  []]  would  indi- 
cate the  correction  to  the  direction  \  ;  [£]  would  indicate  the  correction  to  the  direction  £,  and  [ — 1  +  f] 
would  indicate  the  correction  to  the  angle  156. 


REPORT  OF  PROFESSOR  HARKNESS. 


Proceeding  in  the  usual  manner,*  the  quadrilateral  1465  furnishes  the  angle  equation 

1 80°  =  '5  16+165+651 

and  the  side  equation 

sin  i  5  4  .  sin  5  6  4  .  sin  4  i  6  =  sin  4  i~5  .  sin  4  5  6  .  sin  164 
from  which  we  derive  the  equations  of  condition 

o  =  +  2.4-m+m-m  +  m-m  +  m 

o  =  +  83.3  -  35.8  [i]  +  30.7  in  -  i6.s  [*]  -  42.8  [«]  -  5.2  [M  +  4.i  m 

+     i.ifSR    5-i  [?]  +  59-3  [J] 
The  quadrilateral  1365  furnishes  the  side  equation 

sin  153.  sin  5  6  3 .  sin  3  i  6  =  sin  3  i  5  .  sin  3  5  6 .  sin  i  6  3 
from  which  we  derive  the  equation  of  condition 

o  =  +  43.5  -  3°-o  m  +  25.7  til  - 14.8  m  -  32.2  [i]  -  5.2 1? i  +  3.3  tf ] 
+  1-9  m+  4.3  m  +  47-0  [ii 

These  three  equations  of  condition  give  rise  to  the  following  : 

Equations  of  Correlatives. 


0 

aKi 

(5K2 

dCj 

3 

1 

-     5.2 

4 
1 

-     5-2 

1 

+      i 

+     i.i 

+     1.9 

5 

i 

+     4-1 

+     3-3 

1 
r> 

—       i 

-  35.3 

-  30.0 

I 

+   25.7 

I 

+  3°-7 

1 

+       i 

+     5-i 

+     4-3 

i 

+      i 

+  59-3 

+  47-0 

I 

—  32.2 

\ 

-  42.8 

I 

—       i 

-   16.5 

-  14.8 

The  resulting  normal  equations  are, 

o  =  +    2.4+      6.0 


94-7 


I. 
II. 


III. 


°  =  +  83-3  +  II3-7        +  79I5-8       +4H2.8 
°=+43-S+    94-7        +4142.8       +5085.4 
The  solution  gives 

KI  =  —  0.306 

K2  =r  —  0.00808 

K3  =  +  0.00372 

Substituting  these  values  in  the  equations  of  correlatives,  we  obtain  the  "  Corrections  by  adjustment" 
given  in  the  fourth  column  of  the  table  of  corrected  and  adjusted  directions.  Applying  the  corrections  by 
adjustment  to  the  corrected  directions,  we  obtain  the  adjusted  directions  given  in  the  fifth  column  of  the 
same  table  ;  and  by  means  of  these  adjusted  directions  the  whole  triangulation  has  been  computed,  as  fol- 
lows —  the  lengths  of  the  sides  being  given  in  meters  : 


'See  a  paper  by  Charles  A.  Schott,  esq.,  in  the  United  States  Coast  Survey  report  for  1854,  page  80*  ft  seq. 


66 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


No. 

Denomination. 

Observed 
Angles. 

Corr.  by 
Adjustment. 

Plane  Angles  and 
Distances. 

Logarithms. 

North  Base  —  South  Base  .... 
Stone  Gun-Platform      

23       8.5 

36 

I37I-4 
23       7     54 

3.13716 
0.40578 

North  Base         

131     27.0 

49 

131     26     II 

9.87488 

I. 

25     26.9 

—         59 

25     25     55 

9.63290 

Stone  Gun-Platform—South  Base     . 
Stone  Gun-Platform  —  North  Base     . 

2617.1 
1499.1 

3.41782 
3.17584 

North  Base  —  South  Base  .... 

I37I-4 
3°     53     31 

3.I37I6 
0.28952 

North  Base                     

108     38.5 

-         26 

108     38       4 

9.97662 

II. 

South  Base                       

40     28.9 

29 

40     28     25 

9.81231 

Cathedral  —  South  Base      .... 
Cathedral  —  North  Base      .... 

2531.1 
1733-8 

3.40330 
3-23899 

Stone  Gun-Platform—North  Base     . 
Cathedral       

I499-I 
58     48     n 

3.I7584 
0.06784 

98     24.0 

—         18 

98     23     42 

9-99S32 

III. 

North  Base          

22      48.5 

23 

22      48         7 

9-58833 

Cathedral  —  North  Base      .... 
Cathedral  —  Stone  Gun-Platform  . 

1733-8 
679.2 

3.23900 
2.83201 

North  Base  —  South  Base  .... 

I37L4 
30      31      II 

3.13716 
0.29428 

112          1.5 

5 

ri2       i     25 

9.96709 

IV. 

South  Base                     

37     27.4 

0 

37     27     24 

9.78402 

Chiesa  del  Collegio  —  South  Base     . 
Chiesa  del  Collegio  —  North  Base     . 

2503.4 
1642.3 

3-39853 
3.21546 

Stone  Gun-Platform  —  South  Base     . 
Chiesa  del  Collegio       

72       4.5. 

+         r5 

2617.1 
95     53     46 
72       4     45 

3.41782 
0.00230 
9-97840 

V. 

12        0.5 

+         59 

12          I       29 

9.31876 

Chiesa  del  Collegio—  South  Base     . 
Chiesa  del  Collegio  —  Stone  Gun-Pi. 

2503.3 
548.1 

3-39852 
2.73888 

North  Base  —  South  Base  

I37L4 

31       o     24 

3-I37I6 
0.28808 

92    20.  o 

—           20 

92       19      40 

9  .  99964 

VI. 

56      40.3 

—           22 

5f>     39     56 

9.92193 

Light-House  —  South  Base 
Light-House  —  North  Base 

2660  .  o 
2224.2 

3.42488 
3.34717 

REPORT  OF  PROFESSOR  HARKNESS.  67 

For  the  determination  of  the  azimuths  of  the  sides  of  the  triangles,  we  have  the  following  angles, 
measured  at  the  Stone  Gun-Platform,  late  in  the  afternoon,  between  the  Belvedere  Tower  and  the  sun.  The 
instruments  employed  were  my  six-inch  sextant,  Stackpole  &  Brother  No.  937,  and  the  mean  time  chro- 
nometer T.  S.  &  J.  D.  Negus,  No.  1115. 


Date. 

Time  by  Negus  1115. 

Angle  between  Sun 
and  Tower. 

Limb 
observed. 

1870. 

h.    ra.         s. 

0              ,                » 

December  13 

2     45       4-5 

59     45     20 

L. 

45     5S.5 

59       4     30 

R. 

46     35-5 

58     57     3" 

R. 

47     20.0 

59     22"    10 

L.  . 

December  15 

2       8     54.0 

66     41       o 

L. 

10     18.0 

65     52     40  . 

R. 

II     33-0 

39     3« 

R. 

12       36.0 

58     10 

L. 

December  16 

2     15     35-5 

.    65     31     50 

L. 

16       9.0 

64     54     20 

R. 

16     42.5 

64      48       20 

R. 

17     12.0 

65       13       20 

L. 

In  order  to  obtain  the  zenith  distance  of  the  Tower,  I  measured  with  my  pocket-sextant  Stackpole  & 
Brother  No.  346,  the  angle  included  between  the  Tower  and  its  image  reflected  from  the  inclined  plane  of 
my  black-glass  artificial  horizon.  For  the  reduction  of  these  observations  I  have  employed  the  formula 


in  which 

J=zenith  distance  of  object  observed, 

w=angular  distance  between  the  object  and  its  reflected  image, 

«=angle  included  between  the  inclined  reflecting  plane  and  a  truly  level  surface. 

In  my  apparatus  there  are  two  inclined  black-glass  reflectors,  designated  respectively  as  A  and  B.  For 
A,  "=34°  58'-8;  and  for  B,  61=44.0  59'.  i.  When  using  them  care  was  taken  to  place  them  truly  at  right 
angles  to  the  vertical  plane  passing  through  the  eye  of  the  observer  and  the  object  to  be  observed.  The 
following  are  the  observations,  together  with  their  deduction  : 


Date      

Inclined  plane 

A 

B 

Observed  values  of  m 

72     24 

92     19 

24 

20 

24 

21 

Mean     .... 

72      2d   O 

Index  Correction 

O.O 

0.0 

Eccentricity 

-             O.g 

0.8 

m 

72      23.1 

92     19.2 

(90°  +  a) 
A 

124      58.S 

88     47.2 

134     59-1 
88     49.5 

68 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


The  mean  of  the  two  values  of  A  is  88°  48'. 4,  which  I  have  adopted. 
For  the  determination  of  the  sun's  azimuth  we  have  the  formula 


tan  M  = 


tan  A  = 


tan  t.  cos  M 


'  cos  t  sin  (  y  —  M) 

where  A  is  to  be  taken  greater  or  less  than  180°,  according  as  /  is  greater  or  less  than  180°. 
A=;azimuth  of  object,  counted  from  the  south  around  by  the  west. 
'5=declination  of  object. 
/=hour  angle  of  object. 
9>=latitude  of  place  of  observation. 
The  principal  steps  in  the  computation  of  the  azimuth  of  the  Tower  will  therefore  be  as  follows 


. 

December  13. 

December  15. 

December  16. 

Mean  of  Observed  Times      . 

h.  m.         s. 
2     46     14.6 

I          2      43.3 

h.  m.         s. 

2     10    52.5 

I       2     44  .  4 

h.  m.         s.     j 
2     16     24.8 

I       2     44  .  7 

Local  Mean  Time  

3     48     57-9 

+                 ^      ^2    8 

3     13     36.9 
+             435-9 

3     19      9-5 
+             4       6.6 

/         

3     54     30.7 

3     18     12.8 

3     23     16.1 

s      

-   23     10     46 

-  23     17     38 

-    23      20      25 

<t>        .     .     

4-   37       3     53 

+37      3     53 

+37       3     53 

M                   '. 

-  39     26     12 

-  33     34     13 

-   34     19     55 

(<t>     M) 

+   7°     3°      5 

+  70     38      6 

+   71     23     48 

Sun's  Azimuth        
Mean  of  Observed  Z  s,  Sun  and  Tower 

52     29     16 
59     17     22 
19 

46      o    48 
66       2     50 
36 

46     54     33 
65       6     58 
13 

Corrected  /,  Sun  and  Tower 
Zenith  Distance  of  Tower     .... 

59     J7       3 
88     48     24 
Si     34     54 

66       2     14 

88     48   .24 
76     13     10 

65       6     45 
88     48     24 
76     59    ,  ° 

Horizontal  Z,  Sun  and  Tower   .      .     . 

59       6     40 
III     35     56 

65     35     47 
in     36     35 

64     42     31 
in     37       4 

Taking  the  mean  of  the  three  observed  values,  we  have 

Azimuth  from  Stone  Gun-Platform  to  Belvedere  Tower 
Z  North  Base  and  Belvedere  Tower     .      .      . '  •  .      . 


Azimuth  from  Stone  Gun-Platform  to  North  Base 


O  I  II 

in  36  32 

25  24  7 

86  12  25 


The  azimuths  of  such  other  of  the  sides  as  were  required,  together  with  the  differences  of  latitude  and 
longitude,  have  been  computed  by  means  of  the  formulae  and  tables  of  the  United  States  Coast  Survey.* 
The  results  are  appended.  The  columns  headed  "  Azimuth  "  and  "  Distance  "  contain  respectively  the 
azimuths  and  distances  from  the  stations  named  in  the  first  column  to  those  named  in  the  sixth  column.  The 
column  headed  "  Back  Azimuth"  contains  the  azimuths  from  the  stations  named  in  the  sixth  column  to 
those  named  in  the  first  column. 

•The  formula:  and  tables  are  given  in  the  United  States  Coast  Survey  Report  for  1860,  pp.  361-391.  The  formulae  alone 
are  given  in  my  Report  on  the  Total  Solar  Eclipse  of  August  7,  1869,  Appendix  II  to  the  Washington  Observations  for  1867, 
P-57- 


REPORT  OF  PROFESSOR  HARKM  SS. 


69 


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1 

Mr.  Brothers'  T 

Prof.  Eastman's 

Prof.  Harkness1 

OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMMER  22,  1870. 


IX.— TELEGRAPHIC  DETERMINATION  OF  DIFFERENCES  OF  LONGITUDE. 

If  we  let 

JA  =  difference  of  longitude  between  two  stations;  west  longitudes  being  taken  as  positive  : 
T,  =  time  by  face  of  eastern  clock  when  it  sends  a  signal,  and 

Tw  =  time  by  face  of  western  clock  when  that  signal  is  received  at  the  western  station ; 
T',,,  =  time  by  face  of  western  clock  when  it  sends  a  signal,  and 
T1,  =  time  by  face  of  eastern  clock  when  that  signal  is  received  at  the  eastern  station ; 

/  =  time  occupied  in  the  passage  of  a  signal  from  one  station  to  the  other ; 

JTe,AT't,  J7;t,,and  J 7"',,,= respectively  the  corrections  necessary  to  reduce  the  time  indicated  by 
the  faces  of  the  eastern  and  western  clocks  to  true  local  time  at  the  instants  T,,  T1  „  7',,  7'',,; 
then,  neglecting  personal  equation,  when  the  eastern  clock  sends  and  the  signals  are  received  at  the  western 
station,  we  shall  have 

Al-t=(T,-T«)  +  (ATe-ATlc) 
and  when  the  western  clock  sends,  and  the  signals  are  received  at  the  eastern  station,  we  shall  have 

JA+/=  (T'e—T',t)  +  (J71',.— J7"',,.) 
from  which  we  get 

( T,  —  T,,.)  +  ( T,  —  T',,}     .    ( J  T,  —  J  T,.)  +  ( J  T,.—  J  77,,,) 

.J/,  ^^  -J — : — • —  ._    -4-    - — " — '- -J - LJ. 

2 

( J  T',,  -  J  /''„.)  -(J7,'-  J'/l) 


('/'',  _  7'',,.)-  (T,,-  '/;,. 

2 


If  the  rates  of  the  clocks  are  small,  the  second  term  in  the  expression  for  the  value  of/  may  usually  be 
neglected. 

Difference  of  Longitude  between  Syracuse  and' Malta. 

The  observations  at  Syracuse  were  made  by  me,  at  the  Stone  Gun-Platform,  and  have  already  been 
given  in  detail  on  page  59.  The  observations  at  Malta  were  made  by  Professor  Hall,  with  the  Pistor  and 
Martins  patent  sextant  No.  107,  of  six  inches  radius,  a  mercurial  artificial  horizon,  and  the  mean  time  chro- 
nometer T.  S.  &  J.  D.  Negus  No.  1228.  On  December  13,  he  observed  at  Spencer's  Monument;  on 
December  14,  15,  and  16,  he  observed  on  the  flat  roof  of  the  Telegraph  Office,  which,  according  to  the  Ord- . 
nance  survey  map  on  a  scale  of  i  to  2500.  is  6040  feet  north,  and  760  feet  east,  of  Spencer's  Monument. 
The  reduction  from  the  Telegraph  Office  to  Spencer's  Monument  will  therefore  be,  in  latitude  —59". 73,  and 
in  longitude  +  9".23  =  +  0^615. 

Professor  Hall  obtains  from  his  observations  the  following  results  :* 

Observations  for  Latitude. 


Date. 

Station. 

Object. 

.— 

<J*    <f> 
C-     ° 

*? 

o  «- 
y. 

Observed 
Latitude  of  Sta- 
tion. 

Resulting  Latitude 
of  Spencer's 
Monument. 

1870. 

o         I        n 

0                    t                    II 

Dec.    13 

Spencer's  Monument  . 

Sun      .      . 

16 

+  35  52  55 

+  35     52     55- 

14 

Telegraph  Office    . 

Sun 

12 

54     0 

60.3 

15 

Telegraph  Office     . 

Sun      .     . 

8 

54  23 

83-3 

The  mean  of  the  three  results  is  35°  53'  6"±5".8;  but  as  a  comparison  of  the  adopted  latitude  of 
Syracuse  with  that  obtained  from  Professor  Hall's  sextant  observations  shows  the  latter  to  be  7"  too  large, 
I  subtract  that  amount  from  the  mean  given  above,  and  obtain  finally 

Latitude  of  Spencer's  Monument  =  +  35°  52'  S9"±5".8 


"For  the  observations  in  detail  see  pages  30  to  38. 


•       REPORT  OF  PROFESSOR  HARKNESS. 

Chronometer  7.  S.  &  J.  D.  Negus  No.  1228  slow  of  Local  Mean  Time,  l>\<  Obsen'at'wn. 


Date. 

Station. 

A.  M. 

P.  M. 

Correction  at 
Noon. 

1870. 

h.  m.       s. 

s. 

h.  m.      s. 

December  13 

Spencer's  Monument,  Malta   . 

+  o  57  29.0* 

M 

Telegraph  Office,  Malta     .      . 

28.4 

28.6 

+  o  57  28.5 

15 

Telegraph  Office,  Malta 

28.0 

29.2 

28.  f) 

16 

Telegraph  Office,  Malta      .      . 

•28.7 

29.7 

29.2 

17 

Stone  Gun-Platform,  Syracuse 

+  10  38.9 

39-3 

+  i     o  39.1 

18 

Stone  Gun-Platform,  Syracuse 

38.1 

40.0 

39-0 

«9 

Stone  Gun-Platform,  Syracuse 

38.6 

37-8 

38.2 

21 

Stone  Gun-Platform,  Syracuse 

39-4 

37-5 

38.4 

22 

Stone  Gun-Platform,  Syracuse 

37-2 

Fig.  6. 


*  Reduction  to  Telegraph  Office  =  +  o".6. 

The  telegraph  line  between  Malta  and  Syracuse  is  made  up  of  56^  knots  =  65.1  statute  miles  =  104.8 
kilometers  of  submarine  cable,  and  155.4  statute  miles  =  250  kilometers  of  wire  stretched  in  the  air.  The 
total  length  of  the  line  is  therefore  220^  miles  =  354^  kilometers.  The  battery  at  Malta  consisted  of 
twenty  small-sized  Daniels  cells,  (Pile  Callaud,  Italian  model,)  while  that  at  Syracuse  consisted  of  twenty 
small-sized  Daniels  cells  with  the  liquids  in  contact,  known  in  Italy  as  the  "  Pila  Callaud  a  strozzatura  senza 
diaframma."  The  arrangement  of  the  instruments  on  the  line  was  such 
as  is  never  seen  in  the  United  States,  but  I  believe  it  is  quite  common  in 
Europe.  At  each  station  there  was  a  galvanic  battery,  e,  Fig.  6 ;  a 
polarized  receiving-magnet,  c,  which  recorded  the  signals  with  ink  upon 
a  long  fillet  of  paper  running  at  the  rate  of  about  eight-tenths  of  an  inch 
per  second ;  a  transmitting-key,  b,  having  a  front  and  a  back  contact  ; 
and  an  earth-plate,  d.  The  battery  e  had  one  of  its  poles  connected 
with  the  earth-plate  d,  and  the  other  attached  to  a  point  under  the 
front  contact  of  the  key  b.  The  polarized  receiving-magnet  c  had 
one  end  of  its  coil  connected  with  the  earth-plate  d,  and  the  other  end 
attached  to  a  point  under  the  back  contact  of  the  key  b.  The  line 
wire  a,  coming  in  from  the  distant  station,  was  attached  to  the  axis  of 
the  key  b,  which,  when  not  in  use  for  sending  signals,  habitually  rested 
on  its  back  contact,  and  thus  put  the  line  to  earth  through  the  receiving- 
magnet  c.  Things  being  in  this  condition,  any  current  arriving  from 
the  distant  station  was  at  once  made  evident  by  the  receiving-magnet  c. 
If  it  was  desired  to  send  a  signal  to  the  distant  station,  the  key  b  was 
depressed,  thus  breaking  the  contact  between  the  earth  and  the  line, 
and  establishing  a  connection  between  the  latter  and  the  battery  e.  In 
order  to  render  this  apparatus  as  convenient  as  possible  for  the  exchange 
of  longitude  signals,  I  added  to  it  the  local  battery  /and  the  key  g,  connected  with  the  receiving-magnet 
c,  in  the  manner  shown  in  the  figure. 

The  following  was  the 

PROGRAMME    FOR    THE    DETERMINATION    OF    DIFFERENCE    OF    LONGITUDE. 

I.  Mean  time  box  chronometers,  beating  half-seconds,  will  be  used  at  each  station,  and  their  corrections  and  rates  will  be 
determined  by  means  of  observations  on  the  sun,  made  both  in  the  morning  and  in  the  afternoon,  with  sextants  and  mercurial 
artificial  horizons.  In  order  to  eliminate  constant  errors,  care  will  be  taken  that  the  observations  in  the  morning  and  in  the 
afternoon  are  made  with  the  sun  at  about  the  same  altitude;  that  in  each  case  an  equal  number  of  altitudes  are  taken  on  one  limb 
of  the  sun  with  the  roof  of  the  horizon  in  one  position,  and  on  the  other  limb  of  the  sun  with  the  roof  of  the  horizon  reversed; 
and  that  the  index  error  of  the  sextant  employed  is  well  determined  with  each  set  of  observations. 


OBSERVATIONS  OF   THE  ECLIPSE  OF  DECEMBER'22,  1870. 


2.  The  time  of  exchanging  signals  will  necessarily  depend  upon  the  convenience  of  the  Telegraph  Company,  but  about  I  p.  m. 
will  be  the  most  desirable  hour.     At  the  conclusion  of  the  telegraphic  wt>rk  of  each  day,  the  time  of  exchanging  signals  on  the 
day  following  will  be  agreed  upon. 

3.  Signals  will  be  exchanged  in  the  following  manner  :  The  officer  at  Syracuse  will  ask  the  officer  at  Malta  if  everything  is  . 
ready,  and,  upon  receiving  an  affirmative  reply,  he  will  wait  until  his  chronometer  indicates  50  seconds,  and  then  he  will  make  a 
rattle  with  the  key  />,  Fig.  6,  of  his  apparatus.     This  rattle  will  consist  of  ten  or  fifteen  dots  made  at  the  rate  of  about  five  per 
second.     Next  he  will  make  a  series  of  taps  on  the  key  b,  in  exact  coincidence  with  the  beats  of  his  chronometer  at  o,  I,  5,  10, 
15,  20,  25,  30,  35,  40,  45,  50,  55,  o,  I,  5,  &c.,  seconds,  and  this  he  will  continue  for  three  minutes,  ending  at  o  seconds.     Then 
he  will  pause  for  five  seconds,  and  finally  finish  with  a  rattle ;  after  which  he  will  record  the  hour  and  minute  of  the  last  tap 
before  the  rattle.     As  soon  as  the  officer  at  Malta  hears  the  first  rattle  of  the  officer  at  Syracuse,  he  will  start  his  recording 
apparatus,  if  it  is  not  already  running,  and  will  commence  making  taps  on  the  key  g  of  his  instrument,  in  exact  coincidence 
with  the  beats  of  his  chronometer,  and  at  intervals  of  one  second ;  taking  care  to  mark  the  beginning  of  each  minute  by  omitting 
the  tap  corresponding  to  o  seconds  of  the  chronometer.     This  will  be  continued  until  the  arrival  of  the  second  rattle  from  Syracuse, 
when  he  will  cease  tapping,  and  will  record  the  hour  and  minute  corresponding  to  the  last  tap  which  was  omitted  before  the 
arrival  of  the  rattle.     He  will  then  notify  the  officer  at  Syracuse  whether  or  not  his  signals  have  been  properly  received.     If  they 
have  not  been,  they  will  be  repeated ;  if  they  have  been,  the  officer  at  Syracuse  will  telegraph  to  the  officer  at  Malta  the  hour  and 
minute  corresponding  to  his  last  tap. 

The  taps  on  the  Malta  key^-  will  mark  upon  the  Malta  fillet  a  series  of  dots  corresponding  to  the  seconds  of  the  Malta, 
chronometer,  thus  producing  a  time  scale  in  which  the  beginning  of  each  minute  will  be  designated  by  the  omission  of  the  dot 
corresponding  to  o  seconds.  Upon  this  time  scale  the  taps  on  the  Syracuse  key  b  will  record  a  series  of  dots  corresponding  to 
each  fifth  second  of  the  Syracuse  chronometer,  and  the  beginning  of  each  minute  of  that  chronometer  will  be  designated  by  I  wo 
dots  at  an  interval  of  one  second.  The  hour  and  min.ute  of  each  chronometer  corresponding  to  the  beginning  of  one  of  its 
minutes  upon  this  time  scale  being  known,  it  is  evident  that  a  very  accurate  comparison  of  the  two  chronometers  will  be  obtained 
by  simply  reading  off  the  scale.* 

As  soon  as  the  officer  at  Malta  has  been  notified  of  the  hour  and  minute  corresponding  to  the  last  signal  sent  from  Syracuse, 
he  will  ask  the  officer  at  Syracuse  if  he  is  ready  to  receive  signals  from  Malta,  and  upon  receiving  an  affirmative  reply  the  opera- 
tions described  above  will  be  repeated,  except  that  this  time  the  signals  will  be  sent  by  the  officer  at  Malta  tapping  upon  his  key 
b,  and  will  be  received  upon  the  Syracuse  register  c,  while  the  officer  there  is  tapping  seconds  upon  his  key  g. 

The  following  are  the  numerical  details  of  the  work.  Each  line  in  the  columns  headed  "  Number  of 
Signals"  gives  the  number  of  signals  read  off  from  the  fillet,  the  mean  of  which  furnished  the  chronometer 
comparison  recorded  on  the  same  line.  The  headings  of  the  other  columns  will  be  sufficiently  intelligible 
without  explanation,  if  it  is  borne  in  mind  that  the  notation  employed  is  that  given  on  page  70. 

Comparison  of  Chronometers  obtained  by  reading  off  the  Syracuse  Fillet. 


Date. 

No.  of 
Signals. 

Negus  1115  at 
Syracuse. 

Negus  1228  at 
Malta. 

(T'e-T',r) 

1870. 

h.    m.       s. 

h.    m.      s. 

h.  m.     s. 

Dec.    13 

47 

o     30     55.78 

=     o     33     o.oo 

—  o     2     4.22 

M 

34 

3     12     55.52 

=    3     15     o.oo 

4.48 

15 

37 

3     H     55.19 

=    3     17     o.oo 

4.81 

16 

37 

i       9     54.81 

=      I       12      O.OO 

5.19 

Comparison  of  Chronometers  obtained  by  Reading  off  the  Malta  Fillet, 


Date. 

No.  of 
Signals. 

Negus  1115  at 
Syracuse. 

Negus  1228  at 
Malta. 

(T.-TJ 

1870. 

h.     m.     s. 

h.     m.      s. 

h.  m.     s. 

Dec.    13 

40 

O      21       O.OO      — 

=    o    23     4.23 

—  o     2     4.23 

14 

33 

3     17     o.oo    = 

=    3     19    4-43 

'4-43 

13 

30 

3     25     o.oo    = 

:       3       27       4.76 

4.76 

16 

35 

I       3     o.oo    = 

=     I       5     5-24' 

5-24 

*  From  a  discussion  of  164  signals,  exchanged  between  Syracuse  and  Malta,  Professor  Hall  finds  that  the  probable  error  of 
a  chronometer  comparison  made  by  means  of  a  single  signal  is  only  -j-  0.034  of  a  second. 


REPORT  OF  PROFESSOR  IIARKNESS. 


73 


The  probable  error  of  a  chronometer  comparison  obtained  from  the  mean  of  thirty  signals  is  about 
i  o8. 007. 

As  the  rates  of  the  chronometers  were  small,  I  assume  ATe  =  J71',,  and  J7,,,  =  AT'W.  By  means 
of  a  simple  interpolation  the  tables  on  pages  59  and  71  furnish  the 

Chronometer  Corrections  at  the  Time  of  the  Exchange  of  Signals. 


Date. 

Negus   1115  at 
Syracuse. 

Negus   1228  at 
.Malta. 

(&T,-ATW) 

1870. 

h.    in.         s. 

h.    m.        s. 

h.   m.         s. 

Dec.    13 

+  i       2     43.20     +  o     57     29.55 

+  o       5     13.65 

14 

43-95 

28.52 

15.43 

IS 

44.41 

28.70 

I5-7I 

16 

44.70 

29.25 

15-45 

Resulting  Differences  qf  Longitude  and  ]]'are  limes. 


Date. 

Wt-T'j 

KT.-T,) 

(&T.-AT*) 

AA 

t 

1870. 

h.    m.     s. 

h.    m.     s. 

h.   m.      s. 

h.   m.     s. 

s. 

Dec.    13 

—  O       I       2.  II 

—  O      I      2.12 

+  o     5     13.65 

+  03     9.42 

+  O.OI 

14 

2.24 

2.22 

15-43 

10.97 

—    .02 

'5 

2.41 

2.3S 

15.71 

10.92 

-    .03 

16 

2.60 

2.62 

15-45 

10.23 

+      .02 

The  negative  values  of  t  probably  indicate  that  that  quantity  is  less  than  the  personal  equation  of  the 
observers  in  tapping.  If  we  give  half  weight  to  the  result  of  December  13,  we  get 

J/>  =  +  oh  3™  ios.52  ±  os.2i 

Hut  an  application  of  Peirce's  criterion  shows  that  the  result  of  December  13  should  be  rejected;  and  as  the 
time  observations  at  Malta  on  that  day  were  made  on  one  side  of  the  meridian  only,  and  in  consequence 
may  be  affected  by  a  considerable  constant  error,  I  have  discarded  it.  The  mean  of  the  remaining  three 
results  is 

Al  =  +  o11  3"'   io"8.7i  ±  o9. 1 6 

which  I  adopt  as  the  best  value  obtainable  from  our  work.* 

It  would  seem  that  time  determined  by  means  of  sextants  used  in  the  manner  described  above  must 
be  free  from  all  personality;  but,  in  order  to  make  sure  of  this  point,  I  compared  Professor  Hall's  chronometer 
corrections,  given  on  page  71,  with  my  own,  given  on  page  59,  by  means  of  the  chronometer  comparisons 
given  on  page  60.  In  that  way  I  found  that  the  correction  necessary  to  reduce  Professor  Hall's  time  to 
mine  was,  on  December  17,  +  o".i  ;  on  December  18,  +  o". i  ;  on  December  19,  +  os.8;  and  on 
December  21,  +  o3.5.  These  numbers  might  be  taken  as  an  indication  of  a  personal  equation;  but,  as  they 
are  less  than  the  change  in  the  difference  between  the  results  of  the  forenoon  and  afternoon  observations 
on  these  very  days,  I  prefer  to  consider  them  as  accidental  errors,  and  to  assume  that  no  real  personal  equa- 
tion exists. 

*If  we.assume  Professor  Hall's  chronometer  to  have  had  a  constant  rate  from  December  14  to  December  21,  then  each  ol 
the  three  corrections  observed  at  Malta  will  furnish  an  equation  of  condition  involving  the  correction  at  a  given  date,  the  rate, 
and  the  difference  of  longitude  between  Syracuse  and  Malta;  and  each  of  the  four  corrections  observed  at  Syracuse  will  furnish 
an  equation  of  condition  involving  the  correction  at  the  given  date,  and  the  rate.  Solving  these  equations  by  the  method  ol 
least  squares,  the  chronometric  difference  of  longitude  will  be  found  to  be  oh  3™  io".23. 


10— E 


74  OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 

Our  final  result  for  difference  of  longitude  will  therefore  be 


Stone  Gun-Platform,  Syracuse,  east  of  Telegraph  Office,  Malta     . 
Spencer's  Monument,  west  of  Telegraph  Office  at  Malta     . 
Light  on  Maniace  Castle,  east  of  Stone  Gun-Platform,  Syracuse   . 


li.     in.        s. 

o     3  10.71 
+      0-615 
+      0.861 


Light  on  Maniace  Castle,  Syracuse,  east  of  Spencer's  Monument,  Malta  .     o     3     I2.i9ios.i6 


The   English  Admiralty  chart,  dated  December  10,  1869,  gives,  as  the  difference  of  longitude  between 
these  two  points,  o°  47'  24"  =  oh  3"'  g8.6,  a  value  which  is  too  small  by  2S.6  =  39". 

Difference  of  Longitude  between  Malta  and  Gibraltar. 

The  observations  at  Malta  were  made  by  Professor  Hall,  as  described  above.  Those  at  Gibraltar 
were  made  by  Professor  Newcomb,  with  a  Gambey  sextant  of  seven  inches  radius  and  a  mercurial  artificial 
horizon;  and  as  he  observed  in  three  different  localities,  it  is  desirable,  in  the  first  place,  to  determine  the 
reduction  from  each  of  these  localities  to  some  well-marked  position.  In  order  to  accomplish  this  with  as 
much  accuracy  as  possible,  I  procured  a  copy  of  the  English  Admiralty  chart  of  Gibraltar,  dated  July  27, 
1869,  the  topography  upon  which  is  from  the  Ordnance  plan  of  1868,  and  the  scale  of  which  is  i.oo  inch 
to  1031  feet.  Upon  this  chart  the  Signal  Tower  and  the  Base  of  the  New  Mole  were  marked,  and  Pro- 
fessor Newcomb  was  kind  enough  to  point  out  on  it  the  exact  location  of  the  Telegraph  Office  and  the 
approximate  positions  of  the  American  Consul's  House  and  of  his  station  at  Buena  Vista.  Then,  by  means 
'  of  the  ordinates  given  on  page  9  of  his  report,  I  laid  off  the  position  of  Buena  Vista  Station  from  the  Sig- 
nal Tower,  from  the  Base  of  the  New  Mole,  and  from  the  Telegraph  Office.  To  my  surprise  I  obtained 
three  different  points,  two  of  which  fell  in  the  sea.  To  unravel  the  difficulty,  I  laid  down  on  a  piece  of 
tracing-paper  the  relative  positions  of  the  Telegraph  Office,  the  American  Consul's  House,  the  Signal  Tower, 
the  Base  of  the  New  Mole,  and  Buena  Vista  Station,  employing  for  that  purpose  the  scale  of  the  chart  and 
Professor  New-comb's  co-ordinates.  Then  superposing  the  tracing-paper  on  the  chart  in  such  a  manner 
that  the  Signal  Tower  and  the  Base  of  the  New  Mole  marked  upon  the  former  fell  over  the  same  points 
marked  upon  the  latter,  I  found  that  all  the  other  points  marked  on  the  paper  also  coincided  with  the  cor- 
responding points  on  the  chart  as  accurately  as  could  be  expected  when  it  was  considered  that  the  measure- 
ments of  the  ordinates  were  only  made  to  the  nearest  hundred  feet.  Distributing  the  outstanding  differ- 
ences as  evenly  as  possible  among  the  several  known  stations,  I  transferred  the  positions  of  Buena  Vista 
Station  and  the  American  Consul's  House  to  the  chart  with  all  desirable  accuracy  by  pricking  them 
through  from  the  tracing-paper.  From  the  position  of  Buena  Vista  Station  thus  determined  the  ordinates 
of  the  other  stations  were  measured  on  the  chart,  and  the  results  are  given  in  the  columns  .AT  and  Fof  the 
following  table  ;  the  axis  of  X  being  taken  in  the  meridian,  and  that  of  Fin  the  prime  vertical.  The  numbers 
in  the  columns  r  and  A  have  been  computed  from  those  in  the  columns  X  and  Fby  means  of  the  formulae 

F 

tan  A  =  ,r 


f  F2 

r  being  the  distance  and  A  the  azimuth  from  Buena  Vista  to  any  other  station.     The  numbers  in  the  col- 
umns ;•'  and  A1  have  been  computed  from  Professor  Newcomb's  co-ordinates  by  means  of  the  formula: 

F' 

+  F'2  tan^'  =  —- 

JL 


Admiralty  Chart. 

Newcomb. 

/'      / 

X 

Y 

r 

A 

r' 

./' 

in. 

in. 

feet. 

O                  ' 

feet. 

0                  1 

0                  1 

Telegraph  Office       .... 

8.42  N. 

2.12  W. 

8950 

165     51 

8910 

170    58 

+  5       7 

American  Consul's  House 

6.63  .N. 

1.32  W. 

6970 

1  68     45 

6950 

173    23 

+  4     38 

5  .  60  N 

o  S8  E. 

5800 

185     56 

5710 

191       9 

+  5     T3 

Flag-Staff  at  Landing-Place    . 

2.60  N. 

1  .  80  W. 

3260 

'45     iQ 

Base  of  New  Mole  .... 

2.50  N. 

2.08  W. 

3350 

140     14 

3360 

143     27 

+  3     13 

REPORT  OF  PROFESSOR  HARKNESS. 


75 


A  comparison  of  the  distances  in  the  columns  r  and  r1  shows  that  they  are  as  nearly  identical  as  could 
be  expected,  considering  the  rough  nature  of  Professor  Newcomb's  measurements;  but  the  azimuths  in  the 
columns  .7  and  A1  differ  from  each  other  considerably,  as  shown  in  the  column  A'-A,anA  indicate  an  angle 
of  about  live  degrees  between  the  direction  of  the  meridian  employed  by  Professor  Newcomb  and  that  of 
the  Admiralty  chart.  Adopting  the  meridian  of  the  chart,  1  find  the  following  reductions  necessary  in 
passing  from  the  stations  named  to  Buena  Vista: 


Station. 

Reduction  in 
Latitude. 

Reduction  in 
Longitude. 

Telegraph  Office      .... 
American  Consul's  House 
Flag-Staff  at  Landing-  Place    . 

—  i     25.8 
-i       7.6 
—  o    26  .  5 

—  o     26.7 
—  o     16.6 
—  0      22.6 

The  minus  sign  before  a  reduction  in  latitude,  or  longitude,  indicates  that  the  station  to  which  it  belongs 
is  further  north,  or  further  west,  than  Buena  Vista. 

Professor  Newcomb  obtains  from  his  observations  the  following  results:* 

Observations  for  Latitude. 


. 

i« 

Observed 

Resulting 

Date. 

Station. 

Object. 

'B'S 

Latitude  of  Sta- 

Latitude of 

-°  ~ 

tion. 

Buena  Vista. 

1870. 

0             /             II 

0                ,                   II 

Dec.    15 

Telegraph  Office    .      .     . 

Sun 

6 

+  36    8     25 

+  36     6  59.2 

15 

Telegraph  Office     .      .      . 

Polaris 

5 

8     25 

59-2 

20 

Buena  Vista  Station    . 

Sun 

6 

6     44 

44- 

26 

American  Consul's  House 

a  Ceti  . 

5 

7     41 

33-4 

26 

American  Consul's  House 

Polaris      . 

6    ' 

8      12 

64.4 

Taking  the  means,  I  find 


From  the  Sun  and  a  Ceti  .          .          .          .          .          .  +  36       6     45.5 

From  Polaris  .........  61.8 

which  seems  to  indicate  that  the  observations  are  affected  by  a  constant  error  amounting  to  8". i.     Cor- 
recting for  this  error,  I  obtain  finally 

Latitude  of  Buena  Vista  Station  =  +  36°     6'     S3".6  ±  2". 8 


'  For  the  observations  in  detail  see  pages  17  to  21. 


76 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 
Chronotneter  2.  S.  &  J\  D.  Ncgiis,  No.  126$,  fast  of  Local  A  fain  'II me  by  Observation. 


Date. 

Station. 

Object. 

B 

<u 

SC' 

!* 

•0 

55 

Number  of 
Altitudes. 

Correction  u> 
Chronometer. 

d. 

h.    m.        s. 

Dec.      14.95 

Telegraph  Office,  Gibraltar      .      .      . 

Sun    .... 

E. 

4 

-0      22         8.7 

I5.I5 

Telegraph  Office,  Gibraltar     .      .      . 

Sun    .... 

W. 

7 

16.3 

J5-25 

Telegraph  Office,  Gibraltar     .      .      . 

a     Lyrae 

w. 

4 

16.1 

15.40 

Telegraph  Office,  Gibraltar                  .    '         Jupiter    . 

E. 

7 

16.9 

15.42 

Telegraph  Office,  Gibraltar     .     .      . 

a    Andromed;e 

W. 

2 

16.8 

16.32 

Telegraph  Office,  Gibraltar      .      .      . 

a     Lyras 

W. 

5 

14.6 

20.  II 

Dec.      20.34 
21.36 
22.42 
23.01 

Buena  Vista  Station,  Gibraltar     . 

Buena  Vista  Station,  Gibraltar     . 
Buena  Vista  Station,  Gibraltar     . 
Buena  Vista  Station,  Gibraltar     . 
Buena  Vista  Station,  Gibraltar    . 

Sun    .... 

W.          3 

19.1 

—  O      22      20.84 
21  .22 
21.70 

22.7 

Observed  with  Portable  Transit. 

S  stars       

7  stars       

i  star        

The  reduction  of  a  chronometer  correction  from  the  Telegraph  Office  to  Buena  Vista  is  +is.78. 

The  length  of  the  submarine  telegraph  cable  between  Malta  and  Gibraltar  is  1025  knots  =  1389  statute 
miles  =  2235  kilometers.  It  is  worked  by  means  of  condensers,  no  battery  current  being  allowed  to  enter 
the  line.  The  instruments  employed  for  the  purposes  of  communication  are  Sir  William  Thomson's  reflect- 
ing galvanometers.  For  information  as  to  the  method  of  sending  and  receiving  the  longitude  signals  refer- 
ence may  be  made  to  page  24  of  Professor  Newcomb's  report  and  page  41  of  Professor  Hall's  report.  The 
following  are  the  numerical  details  of  the  work: 

Comparison  of  Chronometers  obtained  from  the  Signals  received  at  Malta. 


Number  of 

Negus   1228   at 

Negus  1265  at 

Date. 

Signals. 

Malta. 

Gibraltar. 

(7e       Jr) 

1870. 

h.     m.         s.            h.     m.       s. 

h.    m.        s. 

Dec.    15 

18 

4     47     43-68   =     4     48     o.oo 

—  o    o     16.32 

16 

21 

23     34     43.05   =  23     35     o.oo 

16.95 

Comparison  of  Chronometers  obtained  from  the  Sigtials  received  at  Gibraltar. 


Date. 

Number  of 
Signals. 

Negus  1228  at 
Malta. 

Negus   1265  at 
Gibraltar. 

(rv-r.) 

1870. 

h.    m.      s. 

h.     m.        s. 

h.  m.       s. 

Dec.    15 

18 

4     55     o.oo  = 

=     4     55     17-34 

-o    o    17.34 

16 

17 

23     42     o.oo  = 

=  23     42     18.13 

18.13 

The  probable  error  of  a  chronometer  comparison  obtained  from  the  mean  of  eighteen  signals  is  about 
o'.oi. 


REPORT  OF  PROFESSOR  HARKNESS. 


77 


As  the  rates  of  the  chronometers  were  small,  I  assume  J  Te  =  A  T' „  and  A  Tw  =  A  T'w.  The  correc- 
tions of  the  chronometers  at  the  times  of  exchanging  signals  have  been  obtained  as  follows:  A  simple 
interpolation  among  the  numbers  contained  in  the  table  on  page  71  gives,  for  the  correction  to  the  Malta 
chronometer  on  December  15,  +  o1'  57"'  28S.72.  By  means  of  the  known  difference  of  longitude,  and  the 
telegraphic  comparison  of  chronometers,  the  Syracuse  observations  give,  for  the  correction  of  the  Malta 
chronometer  on  the  same  date,  +  oh  57'"  28s.(ji.  The  mean  of  these  two  results  is  +  oh  57"'  28S.82,  which 
I  adopt.  In  the  same  way,  on  December  16  I  find  the  correction  of  the  Malta  chronometer  to  be,  irom 
the  Malta  observations,  +  oh  57™  2cf.22,  and  from  the  Syracuse  observations,  +  oh  57m  28S.78.  The  mean 
js  4-  o'1  57m  29s.oo,  which  I  adopt.  The  mean  of  Professor  Newcomb's  observations  at  Gibraltar,  on  De- 
cember 15,  gives,  for  the  correction  of  his  chronometer  at  6h  50'"  p.  m.  on  that  day.  —  ou  22'"  i6s.52.  A 
comparison  of  this  correction  with  that  obtained  on  December  20  gives,  for  the  rate  of  the  chronometer, 

—  is. 2 1  per  day,  allowance  having  been  made  for  the  difference  of  longitude  between  the  Telegraph  Office 
and  Buena  Vista.     The  correction  of  this  chronometer,  when  it  indicated  4U  51'"  p.  m.  on  December  15,  was 
therefore  —  oh  22'"   i6s.42.     On  December  16,  at   7h  45"'  p.  m.,  the  observations  make   the  correction 

—  o'1  22"'   i4s.6,  and,  by  interpolating  between  this  result  and  that  ot  the  day  before,  the  correction  at 
nh  38™  a.  m.  becomes   —  o''   22m   i58.2.     If,  on  the  other  hand,  we   carry  forward  the  correction  from 
December  15  by  means  of  the  rate  given  above,  we  get  —  ou  22"'  i78.37.     Collecting  our  results,  we  have 
the  following  table  of 

Chronometer  Corrections  at  the  Time  of  the  Exchange  of  Signals. 


Date. 

Negus  1228 
at  Malta. 

Negus  1265 
at  Gibraltar. 

(&rc-±r,,,) 

1870. 

h.  m.      s. 

h.  m.      s. 

h.  m.      s. 

Dec.    15 

+  o  57  28.82 

—  o  22  16.42 

+  1  19  45.24 

16 

29.00 

15.2 

44-2 

16 

29.00 

17.4 

46.4 

Resulting  Differences  of  Longitude  and  Wave  Times. 


Date. 

K7-.-r.) 

±(T'e-7",,) 

(Are-A7V) 

AA 

t 

1870. 

h.   m.      s. 

h.   m.      s. 

h.  m.      s. 

h.  m.      s. 

s. 

Dec.    15 

—  o     o     8.  16 

—  o    o     8.67  !  +  I   19  45.24 

+  I   19  28.41 

+  0.51 

16 

8.48 

9.06 

44.2 

26.7 

.58 

iG 

8.48 

9.06 

46.4 

28.9 

On  December  13,  14,  15,  and  16,  Negus  1115  was  compared  with  two  other  chronometers  at  Syracuse, 
and,  by  means  of  the  telegraph,  with  the  Malta  chronometer  also.  These  comparisons  show,  beyond  all 
c|iiestion,  that  the  latter  instrument  was  running  regularly,  and,  from  an  interval  of  seven  days,  Professor 
Hall's  observations  give  it  a  daily  gaining  rate  of  os.og,  but  my  own  observations  make  the  rate  zero.  The 
telegraphic  comparisons  of  this  instrument  with  the  Gibraltar  chronometer,  on  December  1 5  and  1 6,  show; 
that  the  latter  was  certainly  gaining  not  less  than  i".oo  per  day,  while  Professor  Newcomb's  time  determina- 
tions on  these  days  give  it  a  losing  rate  of  is.89_  It  therefore  follows  that  at  least  one  of  the  time 
determinations  must  be  affected  by  a  large  error.  That  on  December  1 5  depends  upon  observations  of  four 
different  objects,  three  of  them  being  to  the  west,  and  one  to  the  east,  of  the  meridian,  and  all  giving  nearly 
the  same  chronometer  correction ;  while  that  on  December  16  depends  upon  a  single  set  of  five  altitudes  of 
'/  1-yrse.  Under  the  circumstances  there  cannot  be  the  least  hesitation  in  rejecting  the  latter,  and  with  it 
the  resulting  value  of  A). ,  which  is  +  ih  19™  26s-7..  From  the  method  employed  in  arriving  at  the  other  value 
of  the  Gibraltar  chronometer  correction  on  the  same  day,  it  is  evident  that  the  resulting  A),  depends  almost 
wholly  on  the  time  determination  of  the  isth,  and  I  thereiore  reject  it  also,  and  adopt  the  first  value  given 
in  the  table  above,  namely,  A).  =+ih  19"'  28".4i. 

The  observations  for  time  having  been  made  with  sextants,  used  in  such  a  manner  as  to  eliminate  all 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,   1-7... 


constant  errors,  I  assume  that  they  are  free  from  personal  equation.  The  probable  errors  of  the  chronometer 
corrections,  on  December  15,  areas  follows:  At  Malta  zt  o8.oy,  derived  from  the  discrepancies  between  the 
adopted  correction  and  the  corrections  given,  respectively,  by  Professor  Hall's  observations  and  my  own. 
At  Gibraltar  ±  os.i3,  derived  from  the  discrepancies  between  the  individual  correr.tiuns  and  the  mean  of  the 
whole.  The  probable  error  of  the  telegraphic  comparison  of  chronometers  is  i  os.oi.  Hence  the  prob- 
able error  of  JA  is  .+_  o".i5. 

Our  final  result  for  difference  of  longitude  will  therefore  be  : 


Telegraph  Office,  Malta,  east  of  Telegraph  Office,  Gibraltar  . 
Spencer's  Monument,  west  of  Telegraph  Office,  Malta 
Flag-Staff  at  Landing-  Place,  east  of  Telegraph  Office,  Gibraltar 

Spencer's  Monument,  Malta,  east  of  Flag-Staff,  Gibraltar   . 


IQ     28.41 

—  0.6 1 5 

—  0.271 


•'5 


X.— GEOGRAPHICAL  POSITIONS  DETERMINED  BY  THE  UNITED  STATES  NAVAL 

OBSERVATORY  PARTIES. 

Collecting  our  results,  and  rejecting  superfluous  figures,  we  have  the  following 

Table  of  Geographical  Positions. 

[North  Latitudes  and  West  Longitudes  are  taken  as  positive.] 


Station. 

Latitude. 

Longitude  in  Arc 
from  Greenwich. 

Longitude  in  Time 
from  Greenwich. 

Longitude  in  Time 
from  Washington.  . 

// 

0             /                 » 

h.    m.        s. 

h.    m.        s. 

Flag-Staff  at  Landing-Place,  Gibraltar     . 

+  36       7     20 

+    5     20     45 

+  O      21      23.0 

-  4     46     49.0 

Buena  Vista  Station,  Gibraltar  .... 

36      6     54 

+     5      20      22 

+  O      21      21.5 

4     46     50-5 

Spencer's  Monument,  Malta      .... 

35     52     59 

-  14     31       8 

-o     58      4-5 

6       6     16.5 

Stone  Gun-Platform,  Syracuse  .... 

37       3     53 

15     18     57 

I         I       15.8 

6       9     27.8 

Prof.  Harkness'  Telescope,  Syracuse. 

37       3     52 

15     18     57 

I         I       15.8 

6       9     27.8 

Prof.  Eastman's  Telescope,  Syracuse. 

.37      3     52 

15     18     58 

I         I       15.9 

6       9     27.9 

Mr.  Brothers'  Telescope,  Syracuse 

37      3     50 

15     18     58 

I         I      15.9 

6       9     27.9 

Light-House  on  Maniace  Castle,  Syracuse 

+  37      3       8 

—  15     19     10 

—  I         I      16.7 

—  6      9     28.7 

Owing  to  a  break  in  the  telegraph  cable  between  Gibraltar  and  Lisbon,  Professor  Newcomb  was  unable 
to  connect  his  station  with  Greenwich,  and  I  have  therefore  made  all  our  longitudes  depend  upon  the  posi- 
tion of  the  Flag-Staff,  at  the  Landing-Place,  in  Gibraltar,  which  I  have  taken  to  be  o1'  21"'  23s.o  west  of 
Greenwich. 

In  order  to  show  precisely  how  much  the  positions  given  by  our  observations  differ  from  those  hereto- 
fore adopted,  I  append  the  following  list,  which  is  made  up  from  the  latest  English  Admiralty  charts.  The 
columns  dL  and  dM  contain  respectively  the  corrections  which  must  be  applied  to  the  latitudes  and  longi- 
tudes of  the  charts  in  order  to  reduce  them  to  our  own. 


Station. 

Latitude. 

if. 

Longitude. 

,/,]/ 

Date  of  Chart. 

Flag-Staff  at  Landing-Place,  Gibraltar 

+  36      7     10 

35     53      ° 

+  10 

-    i 

+    5     20(    45 
—  14    31       o 

0 

-    8 

July  27,  1869 
Aug.  16,  1861 

Light-House  on  Maniace  Castle,  Syracuse    . 

+  37       30 

+    8 

-  15     18     24 

-46 

Dec.  10,  1869 

REPORT  OF  PROFESSOR  HARKNESS. 


79 


XL— MAGNETIC  DECLINATION  AT  SYRACUSE. 

In  order  to  determine  the  magnetic  declination,  I  made  the  following  observations  of  the  bearing  of 
the  Belvedere  Tower,  from  the  Stone  Gun-Platform,  with  my  prismatic  compass,  the  card  of  which  is  divided 
to  single  degrees,  and  numbered  from  o°  to  360° ;  o°  corresponding  to  the  magnetic  south,  and  the  numbers 
increasing  toward  the  west.  It  has  an  index  error  of  +  o°.6.  The  true  bearing  of  the  Belvedere  Tower 
wasN.  68°  23'  W.  =  m°.6. 


Date. 

Time. 

Magnetic  Bearing 
of  the  Belvedere 
Tower. 

Resulting 
Magnetic 
Declination. 

1870. 
Dec.     16 

4.00  p.  m. 

124.0 

12.4  west 

17 

12.30  p.  m. 

124.0 

12.4  west 

18 

9.40  a.  m. 

124.0 

12.4  west 

21 

8.10  a.  111. 

123.9 

12.3  west 

Taking  the  mean,  we  have 

Observed  magnetic  declination 
Correction  for  index  error  of  compass 

True  magnetic  declination 


12°     22'  west. 
-      36' 


11°     46'  west. 


The  probable  error  of  this  result  I  estimate  at  ±  8'. 

XII.— OBSERVATIONS  ON  THE  DAY  OF  THE  ECLIPSE. 

liefore  describing  the  observations  on  the  day  of  the  eclipse,  I  must  not  forget  to  mention  that,  without 
even  a  hint  from  us  that  such  a  thing  would  be  desirable,  the  Prefect  most  kindly  directed  the  military 
commandant,  Lieutenant  Colonel  Augusto  Rossi,  to  furnish  a  sufficient  number  of  troops  to  insure  the 
maintenance  of  order  and  quiet  in  the  neighborhood  of  our  observing  station  on  that  occasion.  For  this 
purpose  the  bastion  was  guarded  by  a  battalion  of  infantry  from  a  little  before  noon  till  after  the  eclipse  was 
over,  and,  although  a  great  crowd  of  people  gathered  in  the  street  opposite,  we  were  enabled  to  make  our 
observations  without  any  interruption.  We  owe  the  Prefect  and  Lieutenant  Colonel  Rossi  sincere  thanks 
for  their  thoughtfulness  in  contributing  to  our  success. 

While  at  Malta  I  was  so  fortunate  as  to  make  the  acquaintance  of  Captain  G.  L.  Tupman,  of  the  Royal 
Marine  Artillery,  who  was  at  that  time  attached  to  the  English  iron-clad  ship  of  war  Prince  Consort.  Being 
an  enthusiastic  amateur  astronomer,  he  became  interested  in  our  expedition  and  most  generously  volunteered 
to  assist  me  in  the  spectroscopic  observations,  by  directing  the  finder  of  my  telescope  to  the  various  parts  of 
the  corona  which  it  might  be  desirable  to  examine.  He  arrived  in  Syracuse  on  the  morning  of  Wednesday, 
December  21,  and  rendered  most  efficient  service,  not  only  during  the  eclipse  itself,  but  also  in  much  of  the 
preliminary  and  subsequent  work.  His  letter  describing  his  observations  forms  Addendum  D  to  this  report, 
and  it  affords  me  great  pleasure  to  place  on  record  an  acknowledgment  of  the  obligations  which  the  expedi- 
tion owes  to  him. 

For  eight  days  after  our  arrival  in  Sicily  the  weather  was  superb ;  but  on  December  20  a  change  took 
place,  the  barometer  began  to  fall,  the  wind  began  to  rise,  and,  although  at  times  the  heavens  were  perfectly 
clear,  still  for  the  most  part  they  were  either  completely  overcast  or  else  necked  with  drifting  clouds,  and 
this  state  of  affairs  continued  long  after  we  left  Syracuse.  However,  at  the  beginning  of  the  eclipse  the  sky 
in  the  neighborhood  of  the  sun  was  perfectly  clear,  and  I  observed  the  first  contact  with  my  three-inch  tele- 
scope, armed  with  a  Huygenian  eye-piece  magnifying  65^  diameters,  at  nh  35™  27".  5  by  the  face  of  the 
chronometer  Negus  1115.  As  the  eclipse  advanced  I  looked  very  carefully  for  the  bright  line  which  was 
shown  in  such  a  marked  manner  along  the  edge  of  the  moon's  limb  in  the  photographs  taken  by  Dr.  Curtis, 
at  Des  Moines,  in  August,  1869,  but,  although  I  used  both  red  and  neutral  tint  shade  glasses,  and  the  defini- 
tion in  the  telescope  was  excellent,  I  could  not  see  any  trace  of  it  till  12''  8IU,  when  I  fancied  I  saw  a  very 
faint  and  narrow  b'right  line,  but  I  am  far  from  being  certain  that  such  a  line  really  existed.  In  fact,  I  "am 
inclined  to  think  it  was  only  the  effect  of  contrast  between  the  bright  sun  and  the  dark  moon. 


8o  OBSERVATIONS  OF   THE  ECLIPSE  OF  DECEMBER  22,  1870. 

With  the  assistance  of  Captain  Tupman,  about  i2h  20™  I  attached  the  spectroscope  to  the  telescope, 
applied  the  necessary  counterpoises,  placed  the  slit  so  that  it  was  inclined  from  a  vertical  circle  about  ten  or 
fifteen  degrees  toward  the  north,  and  adjusted  the  needle  in  the  finder  so  that  when  its  point  fell  upon  a 
horn  of  the  solar  crescent  the  image  of  that  horn  fell  accurately  within  the  jaws  of  the  slit.  A  quarter  of 
an  hour  before  totality  a  dense  cloud  came  over  the  sun  and  hid  it  entirely.  The  wind  was  blowing  half  a 
gale,  and  although  my  telescope,  with  its  solid  substantial  mounting,  was  under  the  lee  of  the  parapet  of  the 
bastion,  it  was  far  from  being  so  steady  as  was  desirable.  When  I  tried  to  light  my  lanterns  I  found  it  was 
impossible,  even  in  the  most  sheltered  place,  and  I  was  obliged  to  take  them  into  the  store-house  and  light 
them  there.  In  carrying  them  back  to  the  telescope  one  was  blown  out,  but  by  crouching  down  behind  the 
parapet  and  sheltering  it  with  our  bodies,  Captain  Tupman  and  I  succeeded  in  lighting  it  again,  after  which 
I  attached  it  to  the  spectroscope  to  illuminate  the  micrometer  scale.  It  was  now  within  less  than  five  minutes 
of  totality,  and  fortunately  the  cloud  covering  the  sun  was  fast  becoming  thinner.  Presently  a  slender  cres- 
cent, which  was  all  that  remained  of  the  solar  disk,  became  visible,  dwindled  rapidly  away,  and  at  ih  o"'  i  i.8o 
I  observed  the  commencement  of  totality  with  my  naked  eye.  The  cloud  was  sufficiently  transparent  to 
allow  the  corona  to  be  seen  through  it,  but,  of  course,  much  diminished  both  in  extent  and  brilliancy,  and  I 
do  not  think  it  was  more  than  half  or  two-thirds  as  extensive  as  that  which  I  witnessed  at  Des  Moines  in 
August,  1869.  On  that  occasion  it  had  a  well-marked  trapezoidal  form,  but  this  time  it  seemed  to  me  to  be 
nearly  circular;  however,  my  view  of  it  was  limited  to  a  mere  glance  at  the  commencement  of  totality,  and 
it  may  have  appeared  differently  afterward.  The  general  illumination  of  the  atmosphere  was  considerable  ; 
in  fact,  it  was  not  really  dark,  for,  in  addition  to  the  outlines  of  objects,  the  details  were  also  visible  to  a  con- 
siderable extent. 

I  spent  the  first  ten  or  fifteen  seconds  of  the  totality  in  examining  the  corona  with  an  Arago  polari- 
scope.  This  instrument  consists  of  a  plate  of  selenite  and  a  double-image  prism,  placed  almost  in  contact 
with  each  other,  and  mounted  in  a  brass  cell,  0.43  of  an  inch  thick,  for  the  purpose  of  slipping  on  to  an  eye- 
piece, so  that  it  may  be  used  for  telescopic  observation.  The  eye-piece  contains  a  diaphragm  of  such  diam- 
eter that  when  it  is  seen  through  the  polariscope  two  circular  fields  of  view  appear,  tangent  to  each  other; 
and  if  polarized  light  is  present  these  fields  of  view  are  of  complementary  colors.  When  the  cell  is  removed 
from  the  eye-piece  its  field  of  view  has  no  longer  any  well-defined  boundary,  and  if  a  beam  of  polarized 
light  is  then  examined  with  it  the  effect  of  the  prism  will  be  to  displace  one  portion  of  the  beam  upon 
another,  and  no  complementary  colors  can  appear  except  at  the  very  edge  of  the  field.  Now,  bearing  in 
mind  that  the  separating  angle  of  the  prism  is  2°  31',  let  us  apply  this  to  the  case  of  the  eclipse.  Looking 
at  the  corona  through  the  polariscope,  two  images  of  it  will  be  seen  well  separated  from  each  other,  and 
everywhere  else  one  portion  of  the  sky  will  be  displaced  upon  another  portion  2°  31'  distant.  Under  these 
circumstances,  no  matter  whether  the  sky  is  polarized  or  not,  it  can  exhibit  only  its  natural  color,  unless, 
indeed,  the  polarization  varies  so  rapidly  that  its  difference  at  points  2°  31'  apart  is  sensible  in  the  instrument. 
If  the  corona  is  polarized  in  the  same  plane,  and  to  precisely  the  same  extent,  as  the  surrounding  sky,  the 
two  images  of  it  will  also  appear  of  their  natural  color;  but  if  it  is  either  more  or  less  polarized  than  the 
surrounding  sky  these  images  will  be  of  complementary  tints,  and  the  arrangement  of  the  tints  will  show 
whether  the  polarization  is  radial  or  confined  to  a  single  plane.  In  order  to  discriminate  between  the  cases 
where  the  corona  is  polarized  to  an  extent  different  from  the  surrounding  sky,  or  not  polarized  at  all,  it  will 
be  necessary  to  examine  it  with  the  same  polariscope,  provided  with  a  diaphragm  so  arranged  as  to  exhibit 
two  fields  of  view  tangent  to  each  other.  Then,  if  the  corona  is  polarized,  the  two  images  will  be  of  com- 
plementary tints,  while  if  it  is  not  polarized,  they  will  be  01  their  natural  color.  The  experiments  I  tried 
were  therefore  as  follows:  First  I  employed  the  polariscope  provided  with  a  diaphragm,  and  I  saw  that  in 
each  field  the  sky  and  the  corona  were  of  the  same  tint,  but  in  the  two  fields  these  tints  were  complementary 
to  each  other.  Next  I  employed  the  polariscope  without  the  diaphragm,  and  I  then  saw  the  sky  of  its 
natural  color,  and  the  two  images  of  the  corona  also  of  their  natural  color.  Clearly,  the  inference  to  be 
drawn  from  these  observations  is  .that,  so  far  as  the  instrument  was  capable  of  determining,  the  light  from 
the  sky  and  that  from  the  corona  were  polarized  to  the  same  extent;  and  knowing  that  the  polarization  of 
the  sky  is  produced  in  our  own  atmosphere,*  I  infer  that  that  of  the  corona  had  the  same  origin,  and  there- 

*  It  may  be  objected  that  under  the  circumstances  of  a  total  eclipse  we  do  not  know  that  the  polarization  of  the  sky  is  pro- 
duced in  our  atmosphere,  because  the  light  of  the  sky  will  then  be  principally  due  to  the  corona,  and  if  the  liidit  of  the  latter  is 
polarized  that  of  the  former  must  also  be  so.  To  this  I  reply  that  the  quantitative  observations  made  at  Syracuse  by  Mr.  G. 
Griffith,  of  the  English  Expedition,  show  that  the  amount  of  polarization  increased  from  the  moon's  center  outward;  a  fact  which 
can  only  be  accounted  for  by  supposing  the  polarization  to  be  effected  in  our  atmosphere. 


REPORT  OF  PROFESSOR  HARKNESS.  8  I 

fore  that  when  the  light  was  emitted  from  the  corona  it  was  not  polarized  at  all.  As  the  tints  were  faint  it 
was  difficult  to  determine  the  plane  or  planes  of  polarization,  and  I  could  not  spare  time  for  the  attempt. 

Dropping  the  polariscope,  I  sprang  to  the  spectroscope,  and  Captain  Tupraan  directed  it  to  the  corona. 
I  at  once  saw  a  green  line,  but  the  wind  had  blown  out  the  lantern  which  illuminated  the  micrometer  scale, 
and,  in  order  to  determine  the  position  of  the  line,  I  seized  my  second  lantern,  which  was  standing  in  a 
sheltered  place,  held  it  to  the  spectroscope,  glanced  in,  saw  that  the  reading  was  about  the  same  as  at  Des 
Moines  in  1869,  and  before  I  could  determine  it  accurately  the  wind  blew^out.this  lantern  also,  and  I  was 
deprived  of  all  means  of  making  exact  measures.  However,  there  cannot  be  the  slightest  doubt  that  the 
line  in  question  was  the  now  famous  1474,  whose  wave  length  is  531.6  millionths  of  a  millimeter.  Captain 
Tupman  then  directed  the  spectroscope  to  many  different  parts  of  the  corona,  and  wherever  the  light  was 
sufficiently  bright  to  show  anything  I  saw  the  same  green  line.  It  is  difficult  to  say  precisely  how  far  I  traced 
it  from  the  sun,  but  certainly  to  a  distance  not  less  than  from  ten  to  fifteen  minutes.  Once  I  saw  two  other 
fainter  green  lines,  of  a  less  degree  of  refrangibility,  which  I  am  pretty  confident  also  belonged  to  the  corona. 
In  addition  to  these,  I  several  times  saw  a  complete  hydrogen  spectrum,  and  on  each  occasion,  supposing  it  to 
be  due  to  a  prominence,  I  taxed  Captain  Tupman  with  having  the  needle  point  of  the  finder  near  one  of  them. 
Once  or  twice  he  admitted  that  such  was  the  case,  but  in  one  or  two  other  instances  he  denied  it.  Feeling 
certain  that  the  lines  were  produced  by  prominences,  I  paid  little  attention  to  the  circumstance  at  the  time ;  but 
on  talking  over  the  subject  with  the  Captain  afterward,  he  assured  me  that  on  at  least  one  occasion  I  accused 
him  of  having  the  pointer  near  prominences  when  such  was  not  the  case.  This  puzzled  me  considerably, 
but  after  a  little  reflection  I  hit  upon  what  I  think  is  the  true  explanation.  The  slit  of  the  spectroscope  had 
a  length  of  0.20  of  an  inch,  which,  with  the  telescope  employed,  would  give  a  field  of  view  15'  46"  high. 
Hence,  when  the  slit  was  radial  to  the  sun,  one  end  of  it  might  easily  be  upon  a  prominence  when  the 
needle  point  in  the  finder  was  eight  minutes  distant  from  it.  During  the  last  few  seconds  of  totality  the 
thin  cloud  covering  the  sun  became  nearly  dissipated,  and  the  faint,  continuous  spectrum  of  the  corona 
became  visible,  but  before  there  was  time  to  examine  it  the  totality  was  over.  Notwithstanding  the  evidence 
of  the  chronometer,  I  could  scarcely  believe  it  had  lasted  one  hundred  and  two  seconds.  It  seemed  to  me 
but  a  moment,  and  I  felt  far  from  satisfied  with  what  I  had  accomplished.  The  high  wind  and  the  thin 
cloud  over  the  sun  placed  me  at  a  great  disadvantage,  and  prevented  me  from  doing  much  that  would  have 
been  easily  within  my  grasp  under  more  favorable  circumstances. 

Five  minutes  after  the  totality  was  over  the  sky  in  the  neighborhood  of  the  sun  became  perfectly  clear 
and  remained  so  till  the  last  contact,  which  I  observed  at  2h  19'"  os.o.  It  will  be  noticed  that  this  time  is 
considerably  earlier  than  that  given  by  Professors  Hall  and  Eastman,  but,  unless  I  made  a  mistake  of  ten 
seconds  in  reading  the  chronometer,  I  am  unable  to  explain  the  cause  of  the  difference.  The  wind  had 
gone  down,  so  that  my  telescope  was  as  steady  as  the  ground  on  which  it  stood ;  the  definition  was  admi- 
rable, the  power  65}^,  and  I  left  the  eye-piece  under  the  impression  that  I  had  recorded  the  contact  perhaps 
a  little  too  late. 

I  believe  the  following  table  contains  all  the  times  of  contact  observed  at  Syracuse.  The  different 
columns  explain  themselves.  The  adopted  local  mean  time  depends  upon  the  correction  derived  from  my 
own  observations  for  the  chronometer  Negus  1115.  Professor  Hall's  observations  to  determine  the  error  01 
the  chronometer  Negus  1228  would  make  all  these  times  os.5  earlier. 

11— E 


82 


.OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


Tunes  of  Contact  between  the  Limits  of  the  Sim  and  Moon,  observed  at  Syracuse, 
Sicily,  during  the  Total  Solar  Eclipse  of  December  22,  1870. 


Observer. 

Chronometer. 

Contact. 

Observed  Time. 

Local  Mean  Time. 

h.     m.      s. 

h.    m.       s. 

Eastman.      .     .    *. 

Negus     1340 

First      . 

n     3Q     12. 

o     38     18.2 

Griffith    .... 

Negus     1256 

First      . 

37     3°- 

38     35-4 

Hall         .... 

Negus     1228 

First 

•37         TC  . 

•?8     n  f. 

Harkness 

Negus     1115 

First      . 

J  I          JJ' 

35     27.5 

jv       *  j  •  D 
33        13-2 

Tupman  .... 

Negus     1115 

First      . 

35     30. 

3§        15.7 

Eastman. 

Negus     1340 

Second  . 

i       3     51.0 

2        2      57.1 

Griffith    .... 

Negus     1256 

Second  . 

I     51- 

2      5<>-4 

Hall  .     .     .     .      . 

Negus     1228 

Second  . 

2      17.  ^ 

2      56.0 

Harkness 

Negus     1115 

Second  . 

*  I  •  j 
O       II. 

2      56.7 

Tupman. 

Negus     1115 

Second  . 

o      9-5 

2      55-2 

Eastman. 

Negus     1340 

Third     . 

I       5     32.5 

2      4     38.6 

Griffith    .... 

Negus     1256 

Third     . 

3     37. 

4     42.4 

Hall  

Negus     1228 

Third 

4      o. 

4            ^8       t: 

Tupman  .... 

Negus     1115 

Third     . 

i     55- 

t        J**  '  3 

4    40-7 

Eastman. 

Negus     1340 

Fourth  . 

2      22      53.5 

3     21     59.4 

Griffith    .... 

Negus     1256 

Fourth  . 

20      34. 

21     39-4 

Hall  

Negus     1228 

Fourth  . 

21      2O.5 

21     59.0 

Harkness     . 

Negus     1115 

Fourth  . 

19      o. 

21      45-7* 

*  Probably  there  was  a  mistake  of  10'  in  reading  the  chronometer,  and  this  should  be  3h  2lm  55". 7. 

Having  thus  stated  the  facts,  it  only  remains  to  consider  what  light  they  throw  upon  solar  physics 
and  the  phenomena  exhibited  during  eclipses.  This  we  will  now  proceed  to  do. 

Origin  of  the  Bright  Line  seen  along  the  Projection  of  the  Moon's  Limb  upon  the  Solar  Disk  in  Photographs  of 
Eclipses. — This  line  seems  to  have  been  observed  upon  all  photographs  of  solar  eclipses  hitherto  taken,  and 
its  cause  has  been  the  subject  of  much  discussion,  in  which  such  eminent  men  as  Mr.  Airy,  Professor  Challis, 
and  Mr.  De  La  Rue  have  participated.  After  the  eclipse  of  August,  1869,  Professor  Henry  Morton  exam- 
ined the  question,  and  made  some  experiments  which  showed  pretty  conclusively  that  the  phenomenon  is  a 
chemical  effect  produced  in  developing  the  photograph;*  while,  on  the  other  hand,  Dr.  Edward  Curtis, 
in  his  report  on  the  same  eclipse,t  described  other  experiments  tending  to  show  that  it  is  due  to  diffraction, 
and  this  view  he  further  supported  by  a  note  from  Dr.  F.  A.  P.  Barnard,  in  which  an  attempt  is  made  to 
show  that  such  a  bright  line  was  to  be  expected  as  a  consequence  of  the  undulatory  theory  of  light.  Finally, 
in  March,  1870,  Professor  Edward  C.  Pickering  made  a  critical  examination  of  Dr.  Barnard's  theory,  and 
showed  most  conclusively  from  Fresnel's  equations  that  diffraction  was  not  capable  of  producing  the  effect 
which  had  been  attributed  to  it.|  Under  these  circumstances  the  inquiry  naturally  arose  whether  or  not  the 
line  was  visible  to  the  eye  during  the  progress  of  an  eclipse.  Here  again  the  evidence  was  contradictory, 
Professor  Stephen  Alexander  affirming  that  he  saw  it  in  1831,  and  again  at  Labrador  in  July,  i86o,§  while 
Professor  Smith  was  unable  to  detect  it  in  August,  1869.  I  therefore  made  it  an  object  of  special  attention 
during  the  eclipse  of  last  December,  and,  as  already  stated,  I  failed  to  find  it.  On  the  whole,  I  think  we 
are  entitled  to  conclude  that  the  line  has  no  real  existence  during  an  eclipse,  and  that  Professor  Morton's 
explanation  of  its  presence  on  the  photographs  is  the  true  one. 

Is  the  Light  of  the  Corona  Polarized  prior  to  entering  the  Earth's  Atmosphere  ? — As  already  stated,  my  obser- 
vations tend  to  answer. this  question  in  the  negative;  but  the  evidence  afforded  by  other  observers  is  so 
conflicting  that  the  matter  cannot  be  regarded  as  settled,  and  must  be  an  object  of  further  investigation  in 
future  eclipses. 

Spectrum  of  the  Corona. — All  parts  of  the  corona  which  are  sufficiently  near  the  sun  give  a  faint  but  abso- 

*  Journal  of  the  Franklin  Institute,  December,  1869,  Vol.  58,  p.  373. 
t  Washington  Observations  for  1867,  Appendix  II,  pp.  135  to  141. 
t  Journal  of  the  Franklin  Institute,  April,  1870,  Vol.  59,  p.  264. 
f  United  States  Coast  Survey  Report  for  1860,  p.  241. 


REPORT  OF  PROFESSOR  HARKNESS.  83 

lutely  continuous  spectrum,  crossed  by  a  single  bright  line,  whose  wave  length  is  531.6  millionths  of  a  milli- 
meter ;  and  as  the  spectroscope  is  moved  outward  from  the  sun  the  light  gradually  vanishes,  the  continuous 
spectrum  disappearing  first,  and  afterward  the  bright  line.  Judging  from  Professor  Young's  observations  in 
August,  1869,  and  from  Father  Denza's  and  my  own  in  December,  1870,  I  feel  pretty  certain  that  some 
parts  of  the  corona  give  in  addition  two  other  bright  lines  in  the  green,  which  are  fainter  and  less  refrangible 
than  that  whose  wave  length  is  531.6.  The  origin  of  the  faint  continuous  spectrum  I  attribute  mostly  to 
the  presence  of  a  little  comparatively  cool  hydrogen  in  those  parts  of  the  corona  nearest  the  sun,  but  it  may 
also  be  partially  due  to  the  substance  which  gives  the  bright  line.  This  latter  substance  I  am  inclined  to 
think  is  most  probably  incandescent  vapor  of  iron,  but  it  would  not  be  surprising  if  it  turned  out  to  be  a  new 
element. 

Physical  Constitution  of  the  Corona. — That  the  corona  is  partially  self-luminous,  emitting  light  whose 
wave  length  is  531.6,  is  now  universally  conceded ;  but  at  least  one  high  authority  seems  to  hold  the  opin- 
ion that  the  self-luminous  portion  does  not  extend  more  than  from  two  to  six  minutes  above  the  surface  ot 
the  sun,  and  that  all  parts  of  the  corona  outside  of  that  limit  are  produced  by  means  of  reflection  taking 
place  at  some  point  not  definitely  specified.  Let  us  examine  this  theory.  If  there  is  any  reflection  in  the 
case  it  must  happen  in  one  of  three  places,  namely:  i.  In  the  earth's  atmosphere,  under  which  term  I 
include  a  space  extending  not  more  than  one  hundred  miles  from  the  earth's  surface;  2.  Between  the  upper 
limit  of  the  earth's  atmosphere  and  the  moon;  or  3.  In  the  neighborhood  of  the  sun. 

Before  considering  where  the  reflection  takes  place,  it  will  be  well  to  comprehend  clearly  the  circum- 
stances under  which  reflection  is  possible.  Fortunately,  on  this  point  the  experiments  of  Professor  Tyndall 
are  perfectly  decisive.  By  passing  a  powerfully  condensed  beam  of  electric  light  through  his  experimental 
tubes  he  found  that  no  matter  whether  they  were  filled  with  air,  gas,  or  vapor,  so  long  as  they  contained 
neither  dust,  motes,  nor  other  solid  or  liquid  particles,  they  scattered  no  light,  and  it  was  only  when 
such  particles  were  produced  within  them  that  the  presence  of  the  electric  beam  became  sensible.*  We  are 
therefore  certain  that  air,  and  many  other  gases  and  vapors — probably  all  matter  in  the  gaseous  state — is 
absolutely  incapable  of  reflecting  any  light  whatever.  Thus  the  theory  that  twilight  is  partly  due  to  the 
reflection  of  the  sun's  rays  by  the  atmosphere  falls  to  the  ground,  and  we  learn  that  the  only  reflecting 
agents  are  impalpable  dust  and  liquid  particles.  Hence,  the  duration  of  twilight  gives  us  a  measure,  not 
of  the  height  of  the  earth's  atmosphere,  but  of  the  height  to  which  dust  and  liquid  particles  extend  in  that 
atmosphere.  We  shall  have  occasion  to  apply  this  principle  presently. 

The  heat  of  the  oxy-hydrogen  flame  is  sufficient  to  volatilize  almost  all  known  substances,  but  it  will 
not  suffice  to  render  any  gas  incandescent.  For  that  purpose  the  electric  spark  must  be  employed.  We  are 
therefore  certain  that  the  heat  required  to  produce  a  gaseous  spectrum  is  far  greater  than  that  required  to 
volatilize  any  of  the  elements ;  and  as  the  spectroscope  shows  that  that  part  of  the  corona  universally 
admitted  to  be  self-luminous  is  composed  of  incandescent  gas,  we  are  entitled  to  conclude,  with  a  degree  of 
probability  amounting  almost  to  certainty,  that  no  solid  or  liquid  matter  can  exist  in  its  neighborhood.  But 
it  has  been  already  shown  that  gaseous  matter  is  incapable  of  reflecting  light,  and  it  therefore  follows  that 
no  part  of  the  corona  can  be  due  to  reflection  taking  place  at  or  near  the  sun.  This  view  is  also  supported 
by  the  fact  that  what  little  polarization  is  found  in  the  light  of  the  corona  seems  to  be  produced  in  the 
earth's  atmosphere.t  Furthermore,  as  the  light  of  the  photosphere  exceeds  that  of  the  chromosphere  at 
least  500,000  times,  if  any  reflection  takes  place  between  the  sun  and  a  point,  say,  one  hundred  miles  above 
the  earth's  surface,  we  should  expect  the  light  so  reflected  to  be  that  of  the  photosphere,  but  no  photospheric 
light  lias  ever  been  detected  in  any  part  of  the  corona.  Professor  Young  has  indeed  said  that  the  continu- 
ous spectrum  of  the  corona  is  partly  due  to  such  light,  and  has  even  given  reasons  to  account  for  the  absence 
of  Fraunhofer's  lines  in  it  ;\  but  nearly  two  years  ago  I  suggested  that  this  continuous  spectrum  was  probably 
due  to  cool  hydrogen,§  and  lately  Mr.  Lockyer  has  succeeded  in  showing  experimentally  that  this  gas  when 
at  a  comparatively  low  temperature  does  yield  a  continuous  spectrum,  together  with  the  bright  line  F,  and, 
if  I  do  not  misunderstand  him,  he  also  is  now  of  the  opinion  that  it  is  the  cause  of  the  continuous  spectrum 
of  the  corona.||  On  the  whole,  it  seems  certain  that  there  is  no  reflection  anywhere  between  the  surface  of 
the  sun  and  the  moon's  orbit. 

*  See  Tyndall's  Fragments  of  Science,  pp.  246  and  306. 

t  It  will  be  observed  that  no  matter  whether  the  light  of  the  corona  is  polarized  near  the  sun  or  in  the  earth's  atmosphere, 
we  should  expect  the  polarization  to  be  radial. 

t  American  Journal  of  Science,  [3,]  Vol.  I,  p.  311,  and  Vol.  II,  p.  53. 

*  Washington  Observations  for  1867,  Appendix  II,  foot-note  on  page  65. 
11  Nature,  Vol.  IV,  p.  250. 


84  OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 

The  whole  tendency  of  modern  discovery  is  to  show  that  the  earth's  atmosphere  has  a  definite  upper 
limit;  but,  in  order  to  make  as  strong  a  case  as  possible  for  the  theory  that  part  of  the  corona  is  produced 
by  reflection  taking  place  between  the  moon  and  the  earth,  we  will  suppose  that  it  extends  to,  or  beyond, 
the  moon's  orbit.  Then  we  may  compute  the  density  of  the  atmosphere  which  the  moon  would  be  capable 
of  gathering  about  itself  as  follows:  Taking  the  diameter  of  the  earth  to  be  7926  miles,  that  of  the  moon 
to  be  3963  miles,  and  the  moon's  mass  to  be  0.0114  that  of  the  earth,  it  can  be  shown  that  at  an  elevation 
of  6120  miles  above  the  earth's  surface  terrestrial  gravity  will  be  reduced  to  an  equality  with  that  existing 
at  the  moon's  surface.  If  we  assume  that  the  laws  which  govern  the  expansion  of  gases  near  the  earth's 
surface  still  hold  at  that  altitude,  Laplace's  barometrical  formula  will  give  for  the  atmospheric  pressure  there 

— -_  of  an  inch  of  mercury,*  which  will  also  be  the  pressure  at  the  moon's  surface. 

If  we  let 

JV  =  number  of  particles  in  a  unit  of  volume  of  any  gas; 

M=  mass  of  each  particle  ; 

v  =  velocity  of  each  particle; 

then  it  can  be  shown  from  the  mechanical  theory  of  gases  that,  at  the  same  pressure  and  temperature,  both 
jVand  Mi*  are  constant  for  all  gases.t  It  is  well  known  that  the  luminiferous  ether  behaves  in  many  re- 
spects more  like  a  solid  than  a  gas,  and  that  the  vibrations  of  sound  are  longitudinal,  while  those  of  light 
are  transversal ;  but,  for  the  sake  of  getting  a  rough  approximation  to  the  order  of  density  of  the  luminifer- 
ous ether,  we  will  assume  that  this  ether  is  a  gas,  and  that  the  velocity  of  light  in  it  is  the  same  function 
of  its  v  that  the  velocity  of  sound  in  oxygen  and  hydrogen  gas  is  of  their  z/'s.  The  best  authorities  give,  for 
the  specific  gravity  of  oxygen,  1.1056,  and  for  the  velocity  of  sound  in  it,  317.0  meters  per  second;  for 
the  specific  gravity  of  hydrogen,  0.0693,  and  for  the  velocity  of  sound  in  it,  1269.1  meters  per  second. 
These  numbers  give,  for  oxygen,  log  Mv1  =  5.0456;  and  for  hydrogen,  log  Mi>2  =  5.0477.  The  mean  is, 
log  Mv2  =5.0466,  which  I  adopt.f  In  order  to  avoid  all  questions  of  pressure  and  temperature,  I  take  as 
the  velocity  of  light  the  value  found  by  M.  Foucault,  from  experiments  made  in  the  Paris  Observatory,  namely 
298,000,000  meters  per  second. §  Taking  air  as  unity,  this  gives  for  the  specific  gravity  of  the  luminiferous 

ether  — i;  and  as  air  at  the  earth's  surface  supports  a  column  of  mercury  30  inches  high,  it  will  follow  that 

under  the  same  circumstances  the  ether  would  suppor  a  column  -^--inches  high.  Taking  into  consider- 
ation the  fact  that  the  velocity  of  light  found  by  Foucault  in  the  rooms  of  the  Paris  Observatory  scarcely 
differs  from  that  found  in  space  by  means  of  the  eclipses  of  Jupiter's  satellites,  I  think  we  must  admit  that 
the  density  of  the  luminiferous  ether  is  not  affected  by  gravity,  and  that  it  will  probably  be  the  same  at  the 
moon's  surface  as  at  the  earth's  surface.  Now,  comparing  the  density  just  found  for  this  ether  with  that 
computed  for  the  atmosphere  at  the  moon's  surface,  it  will  be  seen  that  the  former  is  62  x  io197  times  greater 
than  the  latter ! 

No  one  can  be  more  sensible  than  myself  of  the  very  great  uncertainty  to  which  these  figures  are  liable ; 
but  after  making  an  enormous  .allowance  for  the  effect  of  errors,  they  would  still  suffice  to  prove  that  th  e 
moon  is  not  capable  of  retaining  an  atmosphere  such  as  ours,  even  if  she  had  once  been  provided  with  it, 
and  that  beyond  a  comparatively  short  distance  from  the  earth's  surface  no  matter  possessing  the  power  of 
reflecting  light  can  possibly  exist,  unless  moving  with  a  velocity  comparable  with  that  of  the  planets. 

We  naturally  come  next  to  the  consideration  of  Oudeman's  theory,  which  he  states  thus  :  "  Both  the 
corona  and  its  beams  have  the  same  origin  as  the  zodiacal  light. "||  As  the  origin  of  the  zodiacal  light  is 
one  of  the  greatest  enigmas  of  astronomy,  this  explanation  would  be  somewhat  difficult  to  understand,  wore 


*  As  some  copies  of  this  report  will  fall  into  the  hands  of  persons  whose  scientific  attainments  are  but  moderate,  and  to 

.    6 
whom  the  notation may  not  be  familiar,  perhaps  it  will  be  well  to  write  this  quantity  out  as  a  decimal  fraction.       It  will 

then   stand  thus : 

oooooc 

0006. 

t  Illustrations  of  the  Dynamical  Theory  of  Gases,  by  Professor  J.  C.  Maxwell.     L.  E.  &  D.  Phil.   Mag.,  1860,  Vol.  XIX, 
p.  30. 

{  Strictly,  these  numbers  are  not  the  logarithms  of  Mv^,  but  of  Afv1  multiplied  by  an  unknown  constant. 

$  Comptes  Kendus,  Nov.,  1862,  p.  796. 

II  Nature,  Vol.  Ill,  p.  26. 


REPORT  OF  PROFESSOR  HARKNESS.  85 

it  not  that  in  another  part  of  his  article  he  attributes  its  production  to  "particles  which  float  in  the  ether" 
between  the  earth's  atmosphere  and  the  sun,  and  thus  reflect  the  solar  light  to  us.  As  already  shown,  the 
duration  of  twilight  furnishes  an  accurate  measure  of  the  height  above  the  surface  of  the  earth  at  which 
particles  capable  of  reflecting  the  sunbeams  can  float,  and  the  result  obtained  in  this  way  is  usually  con- 
sidered to  be  45  miles.  I  am  not  aware  that  any  observations  have  ever  been  made  which  give  a  result  so  great 
as  100  miles.  Employing  Laplace's  barometrical  formula  as  before,  and  expressing  the  density  of  the  air 
in  terms  of  the  height  of  the  column  of  mercury  which  it  can  sustain,  I  find  the  density  at  45  miles  eleva- 
tion to  be  0.0038  of  an  inch,  and  at  too  miles  -5,  or  0.000000087,  °f  an  inch.  As  the  least  of  these  den- 
sities is  more  than  2300  times  greater  than  that  found  above  for  the  luminiferous  ether,  it  does  not  seem 
possible  that  particles  of  any  known  substance  can  float  in  it.  If  any  particles  exist  they  must  therefore  be 
moving  in  orbits  about  either  the  moon,  the  earth,  or  the  sun — in  other  words,  they  must  be  meteoroids. 
The  richest  stream  of  these  bodies  of  which  we  have  any  knowledge  is  that  through  which  the  earth  passes 
annually  on  or  about  November  13,  but  the  most  condensed  portion  of  that  stream  is  only  encountered 
once  in  thirty-three  years.  Our  last  encounter  with  it  was  on  the  night  of  November  13-14,  1867,  and  on 
that  occasion,  during  the  thickest  of  the  shower,  the  officers  on  duty  at  this  Observatory  counted  the  falling 
meteors  at  the  rate  of  3000  per  hour;  from  which  Professor  Newcomb  found  that  on  an  average  there  was 
one  meteoroid  in  900,000  cubic  miles  of  space*.  Clearly,  even  if  the  stream  were  increased  in  density  a 
hundred-fold,  the  sun-light  which  it  would  be  capable  of  reflecting  could  not  produce  any  continuous  illumi- 
nation however  faint.  Thus,  then,  all  the  facts  within  our  knowledge  seem  to  point  to  the  conclusion  that 
no  reflecting  -substance  which  can  have  any  influence  in  the  production  of  the  corona  exists  between  the 
earth's  atmosphere  and  the  sun. 

Now  let  us  examine  the  phenomena  which  are  relied  upon  to  prove  that  the  origin  of  some  part  of  the 
corona  is  due  to  reflection  taking  place  in  the  earth's  atmosphere.  These  phenomena  may  be  classed  as 
follows:  i.  Drawings  of  the  corona  of  one  and  the  same  eclipse  made  by  persons  at  different  places  differ 
from  each  other  greatly.  2.  During  the  eclipse  of  last  December,  Professor  Peirce,  stationed  two  miles 
from  Catania,  Sicily,  saw  the  outer  corona  tinged  rosy-red  over  the  prominences — a  place  where  no  intensely 
heated  hydrogen  could  possibly  exist.t  3.  During  the  same  eclipse,  Professor  Young,  stationed  at  Xeres, 
in  Spain,  saw  the  line  C,  6'  or  7'  from  the  sun,  far  above  any  possible  hydrogen  atmosphere;!  Mr.  Perry, 
also  in  Spain,  saw  a  hydrogen  spectrum  8'  away  from  the  sun;§  and  some  observer  in  Spain,  ||  about  whom 
I  have  not  been  able  to  get  any  definite  information,  seems  to  have  seen  a  hydrogen  spectrum  upon  the 
face  of  the  dark  moon  itself. 

The  light  here  referred  to  as  giving  rise  to  some  part  of  the  corona  by  reflection  in  the  earth's  atmo- 
sphere, I  understand  to  be  that  of  the  chromosphere  and  corona  itself.  The  theory  that  direct  sun-light 
might  be  so  reflected  was  discussed  in  my  report  on  the  eclipse  of  August,  1869,^}  and  it  is  not  necessary  to 
refer  to  it  again  at  present,  more  especially  as  I  believe  it  is  now  universally  admitted  that  such  a  theory  is 
entirely  untenable. 

In  reply  to  the  first  class  of  evidence  adduced  above  to  prove  reflection,  I  would  urge  that  no  reliable 
deductions  can  be  obtained  from  the  differences  existing  between  drawings  made  at  places  some  distance 
apart,  because  it  is  well  known  that  fully  as  great  differences  are  seen  in  drawings  made  by  persons  stationed 
within  a  few  feet  of  each  other.  An  excellent  illustration  of  this  was  furnished  during  the  eclipse  of  last 
December.  A  fleet  of  one  Italian  and  five  English  vessels  of  war  were  at  Aci  Reale,  on  the  coast  of 
Sicily,  trying  to  save  the  English  dispatch-vessel  Psyche,  and  many  drawings  of  the  corona  were  made  by 
the  officers  of  these  vessels  ;  but,  judging  from  the  published  account,  119  two  of  them  were  alike.  In  fact, 
two  sketches  made  on  the  deck  of  the  same  ship,  the  Lord  Warden,  were  so  different  that  it  could  not  have 
been  supposed  they  were  intended  to  represent  the  same  object.**  These  differences  probably  arose  partly 
from  want  of  artistic  skill,  and  still  more  from  the  bewildering  effect  of  the  strange  and  exciting  phenomena 
of  a  total  eclipse  witnessed,  perhaps,  for  the  first  time.  I  have  seen  so  many  instances  of  amateurs  making 

*  United  States  Naval  Observatory  Reports  on  the  November  Meteors  of  1867,  p.  n. 
t  Nature,  Vol.  Ill,  p.  222. 
t  Nature,  Vol.  Ill,  p.  261. 
$  Nature,  Vol.  Ill,  p.  223. 

||  Quoted  by  Mr.  Lockyer  in  Nature,  Vol.  Ill,  p.  223. 

IT  Washington  Observations  for  1867,  Appendix  II,  p.  64.     See  also  Proctor's  Work  on  the  Sun,  p.  357. 
**  Nature,  Vol.  Ill,  pp,  222  and  223. 


86  OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 

magnificent  sketches  of  celestial  phenomena,  which  could  not  possibly  have  existed,  that  I  confess  I  have 
little  confidence  in  any  delineations  of  the  corona  not  made  by  trained  observers  who  were  at  the  same  time 
competent  draughtsmen.  Furthermore,  it  is  a  matter  of  common  experience  that  whenever  a  bright  object 
is  seen  on  a  dark  ground,  that  object  will  appear  to  be  surrounded  by  a  greater  or  less  number  of  very  dis- 
tinct rays.  Yet  no  one  imagines  these  rays  to  be  real.  They  are  purely  subjective,  and  can  be  made  to 
disappear  from  the  most  dazzling  object  by  looking  at  it  through  a  dark  glass,  or  from  a  moderately  bright 
object  by  viewing  it  through  a  telescope  of  low  power.  That  the  corona  exhibits  real  rays  cannot  be 
doubted,  because  they  have  been  photographed  ;  but,  as  it  is  a  bright  object  on  a  dark  ground,  when  viewed 
by  the  naked  eye  it  will  surely  be  surrounded  by  some  spurious  ones  also,  and  therefore  no  confidence  can 
be  placed  in  the  reality  of  the  existence  of  any  faint  rays  which  have  not  been  seen  by  means  of  a  tele- 
scope or  opera-glass.  To  recapitulate,  the  conditions  necessary  for  the  production  of  a  trustworthy  drawing 
of  the  corona  are,  that  the  person  making  it  shall  be  a  trained  observer  and  competent  draughtsman,  and 
that  no  details  shall  be  recorded  which  are  not  visible  through  an  opera-glass. 

Mr.  Lockyer,  in  two  very  able  papers  relative  to  the  eclipse  of  last  December,  lias  said  that  although 
Mr.  Brothers'  photographs  taken  at  Syracuse  show  such  vast  rifts  in  the  corona,  none  of  these  rifts  were 
seen  by  any  of  our  party ;  and  to  this  statement  he  appears  to  attach  considerable  importance.*  I  regret  to 
say  that  he  is  in  error  as  to  the  facts.  The  great  rift  was  seen  by  Professor  Hall,  and  is  mentioned  in  his 
report.! 

As  to  the  second  and  third  classes  ot  evidence  adduced  above  to  prove  that  part  of  the  corona  is  due 
to  reflection  taking  place  in  the  earth's  atmosphere,  I  have  only  to  say  that  they  apply  solely  to  the  eclipse 
of  last  December,  which  happened  at  a  time  when  the  heavens  were  thick  with  haze  and  clouds  of  all 
kinds,  and  no  one  has  ever  for  an  instant  thought  of  denying  that  light  passing  through  such  an  atmosphere 
must  be  more  or  less  reflected.  Manifestly  these  proofs  have  no  application  to  the  case  of  a  clear  and 
transparent  sky,  and  there  is  not  the  slightest  reason  to  suppose  that  the  aspect  of  the  corona  seen  in  such 
a  sky  would  be  any  more  altered  by  it  than  that  of  a  nebula,  or  the  moon,  seen  under  the  same  circum- 
stances. 

In  view  of  the  evidence  which  has  been  discussed,  it  seems  safe  to  conclude  that  when  the  sky  is  per- 
fectly clear  there  is  nothing  between  the  eye  of  the  observer  and  the  solar  surface  which  can  appreciably 
alter  either  the  appearance  or  extent  of  the  corona ;  and  under  such  circumstances,  anything  seen  in  it  by 
the  aid  of  a  properly  adjusted  telescope  may  be  confidently  received  as  representing  phenomena  occur- 
ring at  the  sun  ;  but  if  the  observations  are  made  with  the  naked  eye  the  real  phenomena  will  almost  certainly 
be  more  or  less  complicated  by  subjective  appearances  depending  upon  irradiation. 

From  the  time  of  Dr.  Wyberd  in  1652,  down  to  the  present  moment,  there  have  not  been  wanting  per- 
sons who  say  that  the  corona  exhibits  a  rotary  motion,  but,  as  these  statements  are  expressly  contradicted 
by  nearly  all  observers  of  known  skill,  it  is  not  necessary  to  consider  them  further  here.  There  still  remains 
another  class  of  phenomena  which  cannot  be  dismissed  so  summarily,  because  their  existence  has  been 
affirmed  by  astronomers  of  the  very  highest  reputation.  I  allude  to  variations  in  the  brightness  of  the  corona, 
and  to  rays,  beams,  or  rifts  in  it.  Otto  Struve,  observing  at  Lipesk  in  1842,  found  the  corona  so  bright 
that  the  naked  eye  could  scarcely  endure  it.  Mr.  Airy  has  been  fortunate  enough  to  witness  several  total 
eclipses,  and  he  testifies  that  the  corona  was  much  brighter  in  some  of  them  than  in  others.  The  experience 
of  the  officers  belonging  to  this  Observatory  is  the  same;  the  corona  appeared  much  brighter  in  August,  1869, 
than  in  December,  1870.  The  existence  of  rays,  streamers,  and  rifts  in  it  is  a  matter  of  common  notoriety. 
How  are  these  appearances  to  be  explained  ?  Do  we  know  of  any  other  similar  phenomena  depending  upon 
ascertained  causes  ?  I  think  we  do.  The  sun  is  surrounded  by  a  red  hydrogen  atmosphere,  which  varies  in 
depth,  just  as  the  corona  does.  The  outline  of  this  atmosphere  is  broken  by  vast  protuberances,  correspond- 
ing to  the  rays,  or  streamers,  of  the  corona.  These  protuberances  vary  in  position,  extent,  and  number, 
iust  as  the  rays  or  streamers  do.  And  finally,  these  proturberances  are  sometimes  brighter,  sometimes  fainter, 
depending  upon  the  temperature  of  the  hydrogen  composing  them,  just  as  the  rays  of  the  corona  vary 
in  brightness.  The  analogy  is  complete,  and,  if  we  assume  that  the  luminous  gas  composing  the  corona  is 
ejected  from  the  sun  in  the  same  manner  as  the  red  prominences,  all  the  observed  facts  will  be  accounted 
for;  even  to  such  an  extreme  case  as  that  exhibited  in  the  picture  made  by  Mr.  Oilman  at  Sioux  City, 
Iowa,  in  August,  1869$ — a  picture,  by  the  way,  of  whose  accuracy  I  am  convinced.  Moist  steam  issuing 

•Nature,  Vol.  Ill,  p.  223,  and  Vol.  IV,  p.  232. 

+  See  page  29  of  these  reports. 

\  Washington  Observations  for  1867,  Appendix  II,  plate  12. 


REPORT  OF  PROFESSOR  HARKNESS.  87 

from  a  boiler  at  the  very  moderate  pressure  of  fifty  pounds  per  square  inch  develops  torrents  of  electricity. 
The  best  information  we  possess  indicates  that  the  hydrogen  of  the  red  prominences  is  belched  forth  with 
a  velocity  of  about  one  hundred  and  twenty  miles  per  second,  and  it  does  not  seem  unreasonable  to  sup- 
pose that  it  may  carry  with  it  a  little  spray.  If  it  does,  then,  judging  from  analogy,  the  friction  of  this  spray 
against  the  mouth  of  the  crater  from  which  it  is  escaping  will  probably  generate  electricity  in  quantities  of 
which  we  can  have  simply  no  conception,  and  it  may  very  likely  play  some  part  in  the  production  of  the 
long  streamers  of  the  corona.  In  conclusion,  the  theory  which  I  propose  may  be  stated  as  follows  : 

When  seen  in  a  clear  skv,  tlic  corona  is  a  purely  solar  phenomenon,  produced  by  a  vast  body  of  self-luminous 
gas — not  improbably  incandescent  vapor  of  iron — wliich  envelopes  the  sun  and  is  empted  from  it  in  the  same 
manner  as  the  red  prominences. 
Very  respectfully, 

WM.  HARKNESS, 
Professor  of  Mathematics,  U.  S.  Navy. 
Rear-Admiral  B.  F.  SANDS,  U.  S.  N., 

Superintendent  U.  S.  Naval  Obsematory,  Washington,  D.  C. 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


ADDENDUM  A. 

Observations  of  the  Sun  for  Time,  marie  on  the  Stone  Gun-Platform  at  Syracuse,  Sicily,  by  Professor  IVi/liam 
Harkness,  U.  S.  N.,  with  the  Sextant  Stackpole  &•  Brother  No.  937,  Mercurial  Artificial  Horizon  Ha.  i, 
and  Chronometer  T.  S.  &  y.  D.  Negus  No.  1115. 

[NOTE. — The  barometer  employed  was  a  pocket  aneroid,  1.9  inches  in  diameter,  marked  L.  Casella,  London,  No. 
1128.  It  was  compensated  for  temperature,  and,  in  order  to  reduce  its  observed  readings  to  the  corresponding  readings 
of  a  mercurial  barometer  at  32°  F.,  it  is  only  necessary  to  subtract  from  them  0.12  of  an  inch.] 


SUN      .         .         DECEMBER  13,  1870. 

i 

SUN      .         .         DECEMBER  13,  1870. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc=u. 

Off  Arc  =  u'. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  u. 

Off  Arc=«'. 

33  o 
o 
o 

o         i         n 

359  27  50 
45 
45 

32  50 
33     o 
10 

359  27  45 
40 
40 

o  23.4 

+           7.7 

—          o  20.  8 

+                 8.1 

0    15-7 

o  12.7 

Means 
Index  Corr.,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

47  45     o 
48    o    o 

15      0 

47  30    o 
45     o 
48    o    o 

h.  m.     s. 
8  52  35.0 

53  50.0 
55     6.0 
56  5L5 
58     9.0 
59  27.0 

50    o    o 
10    o 

20      0 

49  30    o 
40    o 
50    o 

ll.    111.        S. 

9     4  25.5 
5    21.  0 

(i  14.0 

7  41-5 
8  36.8 

9  35-o 

47  52  30.0 
15-7 

8  55  59-8 

49  55     o.o 
12.7 

9    (•>  59-" 

.    113    9  48.2 

h.    m.     s. 
10    4  22.5 

—     *,  10  .  8 

.    113     9  50.0 

h.  m.      s. 
10  15  22.4 

5  39.6 

47  52  14-3 

2      8.2 
+                     8.2 

49  54  47-3 
2      2.3 
+                     8.2 

Polar  Distance  of  < 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatio 

Dbject      .     . 
me     ... 

Polar  Distance  of 

Local  Apparent  T 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatio 

Dbject      .      . 
me 

9cft   42    7 

10    9  42.8 

2ter 
of  Local  M.T. 

•        8  55  59.8 

eter    .      .     . 
of  Local  M.T. 

9    &  Sg.o 

I      2    42.9 

..12  43.8 

is  were  made  before  noon. 

is  were  made  before  noon. 

REPORT  OF  PROFESSOR  HARKNESS. 


89 


ADDENDUM  A— Continued. 


SUN       .         .         .         DECEMBER  13. 

SUN      .         .         .         DECEMBER  13, 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  u. 

Off  Arc=u>. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  u. 

Off  Arc  =  oji. 

33   10 
10 

0 

359  27  4° 
40 
40 

32  50 
40 

35 

359  27  40 
50 
50 

o  23.4 
+                 8.5 

o  14.2 

+               3.0 

• 

o  14.9 

O    II.  2 

Means 
Index  Corr.,  &c. 

a 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

0 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

0            1              It 

51  50    o 
52    o    o 

IO      0 
51    20      O 

30    o 

40    o 

h.  m.      s. 
9  M  56.5 
15   56-5 
16  57.5 
18  31.0 
'9  36-5 

20    36.5 

22  45     o 
30    o 
15     o 
22  45     o 

30      0 

15     o 

h.  m.       s. 
2  25     9.5 
26    o.o 

26  49.5 

28  45-5 

29  35.5 
30  25.5 

5i  45     o.o 
-              14-9 

9  i?  45-8 

22   30      0 
II.  2 

2    27   47.6 

Ther.     63. 

in. 
Bar.       30.27 

• 
113     9  51-8 

h.  m.      s. 
10  26    8.9 

5  39-4 

O             '                  II 

113  to  43.3 

h.  m.      s. 
3  36     3-7 

-     5  33-2 

51  44  45-1 
I   57-4 
+                 8.1 

22   29  48.8 

4  39-2 

+                 8.8 

Polar  Distance  of 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronomi 

Chronometer  slow 
These  observatior 

Dbjcct      .     .    • 
me 

Polar  Distance  of  ( 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronomi 

Chronometer  slow 
These  observation 

)bject      .     . 
me     ... 

10   20   29.5 

9  I?  45-8 

3  30  30.5 
2  27  47.6 

:ter     . 
of  Local  M.T. 

ter     .      .      . 
of  Local  M.  T. 

I     2  43.7 

I      2   42.9 

s  were  made  before  noon. 

s  were  made  after  noon. 

NOTE. — The  observations  before  noon  on  December  13  were  made  at  the  Prima  Porta  Terra,  which  is  OM3  east  of 
the  Stone  Gun-Platform. 


12— E 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


ADDENDUM  A— Continued. 


SUN      .         .         .         DECEMBER  13. 

SUN       .         .         .         DECEMBER  14. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc=w. 

Off  arc  =  w!. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  u. 

Off  Arc=<A 

/     " 
32  45 
45 
50 

359  27  50 
28     o 
28     o 

33  10 
15 

20 

359  27  50 
28     o 

27  50 

o  21.7 
+               2.7 

o  34.2 

+                     6.9 

o  19.0 

o  27.3 

Means 
Index  Corr.,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

H 
Refraction 
Parallax 

2  Altitude. 

Chronometer. 

20  45     o 
30    o 
15     o 
20  45     o 
30    o 
15     o 

h.  m.    s. 
2  31  49-0 
32  38.0 

33  27.5 
35  20.5 
36  10.5 
36  59-° 

44     o     o 

15      0 

30    o 
44    o    o 
15     o 
30    o 

h.  m.      s. 
8  35  4I-" 
36  50.0 

37  59-5 
40  40.0 

41  50.0 
43     2.0 

20  30    o.o 

19.0 

2  34  24.1 

44  15     o.o 
27-3 

8  39  20.4 

Ther.     62  .  5 

in. 
Bar.       30.22 

0              1                 II 

.  113  10.44.4 

h.  m.     s. 
.       3  42  40.3 

5  33  -1 

.    113   13  34.1 

h.  m.     s. 
.       9  47  14.7 

20    29    41.0 

5     5-5 
+                8.9 

44  M  32.7 
2   19.7 

+                8.3 

Polar  Distance  of 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronorm 

Chronometer  slow 
These  observation 

Object      .      . 
me 

Polar  Distance  of  ( 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronorm 

Chronometer  slow 
These  observation 

Object 
me 

1.    T.-J      72 

ter 
of  Local  M.  T. 

.       2  34  24.1 

ler 

8  39  20.4 

I      2   43.1 

of  Local  M.T.  .       i     2  42.8 
s  were  made  before  noon. 

s  were  made  after  noon. 

REPORT  OF  PROFESSOR  HARKNESS. 


ADDENDUM  A— Continued. 


SUN       .         .         .         DECEMBER  14. 

SUN       .         .         .         DECEMBER  14. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  w. 

Off  Arc=u>. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc=w. 

Off  Arc  =  w'. 

/     // 
33    o 

0 
IO 

359  27  50 
50 
50 

33  15 
o 

15 

359  27  40 
40 

5° 

o  26.6 

+          7.5 

o  26.6 

+          7.9 

o  19.  i 

o  18.7 

• 

Means 
Index  Corr.,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

a 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

47  10    o 
20     0 

30    o 
46  40    o 
50    o 
47    o    o 

h.  m.       s. 
8  50  43-5 
51  32.0 
52  22.5 
53  38.5 
54  29-0 
55  19-5 

49    o    o 

10      0 

20    o 
48  30    o 
40    o 
50    o 

h.   m.     s.. 
9    o     7-5 
i     0.5 
i  55-5 
3   13.0 
4  10.0 
5     3-5 

47     5     o.o 
19.  1 

S  53     0.8 

48  55     o.o 
18.7 

9     2  35.0 

.    113  13  36.2 

h.   m.     s. 

.      10    o  55.9 

—     5  ii.  2 

Ther.     63.5 

in. 
Bar.      30.28 

.    113  13  37.6 

h.  m.     s. 
10  10  30.6 

—     5  ii.  o 

47    4  40.9 
2  10.5 
+                 8.3 

48  54  41.3 
2     5-1 

+                       8.2 

Polar  Distance  of 

Local  Apparent  T 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatio 

Dbject      .      . 
me 

Polar  Distance  of 

Local  Apparent  T 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatio 

3bject      .      . 
me 

9  55  44-7 
8  53    0.8 

10     5  19.6 
9     2  35.0 

eter     .     .     . 
of  Local  M.  T. 

ster     .     .     . 
of  Local  M.  T. 

I       2    43.9 

I      2   44.6 

is  were  made  before  noon. 

is  were  made  before  noon. 

OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


ADDENDUM  A— Continued. 


SUN      .         .         .         DECEMBER  14. 

! 

SUN      .         .         .         DECEMBER  14. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc=u. 

Off  Arc  =ui. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  o. 

Off  Arc  =  u1. 

32  40 
50 

45 

359  28  10 

0 
0 

32  40 
30 
40 

359  28     o 
27  50 
27  55 

o  24.1 

+                3-8 

o  15.8 
+                3-5 

o  20.3 

o  12.3 

Means 
Index  Corr.,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

a 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

26  50    o 
40    o 
30    o 
27  10    o 

0      O 

26  50    o 

h.  m.     s. 
2  ii  21.5 

ii  56.5 

12    31.0 

13  57-0 
'4  31.5 
15     5-5 

25  20    o 
10    o 
o    o 
25  50    o 
40    o 
30    o 

h.  m.     s. 
2  16  32.0 

17     7.0 
17  41.0 
18  3iso 
19     5-5 
19  39-5 

26  50    o.o 
20.3 

2    13    13.8 

25  25    o.o 
-              ".S 

2  18     6.0 

0              /               II 

.     113    14    23.2 

h.  m.      s. 
3  21     2.8 

.     —     5    4.8 

.   113  14  23.9 

h.  m.     s. 
•       3  25  55.0 

—     5     4-7 

26  49  39.7 

3  55-5 
+                8.8 

25  24  47.7 
4     8.7 
+                8.8 

Polar  Distance  of 

Local  Apparent  T 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observalioi 

Object      .     . 
me 

Polar  Distance  of 

Local  Apparent  T 

Equation  of  Time 

• 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatio 

Object      .      . 
nve 

3  J5  58.0 

3  20  50.3 

eter     . 
of  Local  M.  T. 

2  13  13.8 

eter 
of  Local  M.  T. 

2  18    6.0 

i     2  44.2 

i     2  44.3 

is  were  made  after  noon. 

is  were  made  after  noon. 

REPORT  OF  PROFESSOR  HARKNESS. 


93 


ADDENDUM  A— Continued. 


SUN      .         .         .         DECEMBER  14. 

SUN      .         .         .         DECEMBER  15. 

Index  Corr. 
E 

Index  Corr.,  &.c. 

On  Arc  =  w. 

Off  Arc  =u'. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =«. 

Off  Arc  =  u». 

32  40 
40 
50 

339  28     o 

0 
0 

33     o 

10 

20 

359  28  15 
10 
10 

0   21.6 

4-                 3-2 

o  40.8 

+                     5-2 

o  18.4 

o  35-6 

Means 
Index  Corr.,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

23  30    o 
20    o 
10    o 
24    o    o 
23  50    o 
40    o 

h.  m.      s. 
2  22  49.0 

23  22.5 

23  55-5 
24  44.0 
25  iS.o 
25  52.0 

35  10    o 
20    o 
30    o 
34  40    o 

50     0 

35     o    o 

h.   m.     s. 
801.0 

o  39-5 
i  17-5 

2    I5.O 

2  53-o 
3  32.5 

23  35     o.o 

18.4 

2    24    20.2 

35     5     o.o 
35-6 

8     i  46.4 

Ther.     61.0 

in. 
Bar.       30.23 

.    113  14  24.7 

h.  m.      s. 

3  32     8.2 

.    113  16  50.2 

h.  m.     s. 
9     9  r3-6 

23  34  41-6 
4  27.8 
+                 8.8 

35     4  24.4 
3     o.o 
+-                8.6 

Polar  Distance  of 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatio 

Object      .      . 
me 

Polar  Distance  of  < 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  obscrvatior 

Dbject 
me 

o    27      ^6 

eter     . 
of  Local  M.  T. 

2    24    20.2 

2ter 
of  Local  M.T. 

8     i  46.4 

I       2    43.4 

i     2  43.8 

is  were  made  after  noon. 

is  were  made  before  noon. 

94 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


ADDENDUM  A— Continued. 


\ 

SUN      .         .         .         DECEMBER  15. 

SUN       .         .         .         DECEMBER  15. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  <J. 

Off  Arc  =  <J1. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  w. 

Off  Arc  =  ui. 

32  50 
33     o 
32  50 

359  28     o 

0 

o 

33  10 
o 

IO 

359  28     o 

0 

o 

0    26;6 

+               5-5 

o  33-4 
+                 5-8 

O   21.  I 

o  27.6 

Means 
Index  Corr.,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

37     o    o 

IO      O 

20    o 
36  30    o 
40    o 
50    o 

h.  m.      s. 

8     7     5-5 
7  47.0 
8  26.0 

9  25.5 
10    5.0 

10  45-5 

38  30    o 
40    o 
50    o 
38     o    o 

10      0 
20      O 

h.  m.     s. 
8  13     6.0 

13  46-5 
14  27.5 
15  27.5 
16     9.5 
16  50.0 

36  55     o.o 

21.  I 

8     8  55.8 

38  25     o.o 

27.6 

8   14  57-8 

.   113  16  51.1 

h.  m.     s. 
9  16  24.1 

—      4A-32 

Ther.     60. 

in. 
Bar.       30.27 

.    113  16  52.0 

h.  m.     s. 

9  22  25.5 

—     4  43.  I 

36  54  38-9 
2  50.7 
+                8.6 

38  24  32.4 

2  43-7 
+                8.5 

Polar  Distance  of 

Local  Apparent  T 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatio 

Object      .      . 
me      ... 

Polar  Distance  of 

Local  Apparent  T 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatio 

Object      .      . 
me 

\ 

Q    II    4O   Q 

9  17  42.4 

eter     .      .     . 
of  Local  M.  T. 

.        8     8  55.8 

eter 
of  Local  M.  T. 

.        8   14  57.8 

I     2  45.1 

I      2   44.6 

ns  were  made  before  noon. 

ns  were  made  before  noon. 

REPORT  OF  PROFESSOR  HARKNESS. 


95 


ADDENDUM  A— Continued. 


SUN       .         .         .         DECEMBER  15. 

SUN      .         .         .         DECEMBER  15. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  u. 

Off  Arc  =  W. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  w. 

Off  Arc=u1. 

33  30 
30 
30 

359  28  10   * 
10 
o 

33  20 
15 
15 

359  28  10 

5 
o 

o  48.4 
+                5-4 

o  40.8 

+                     5-2 

o  43-0. 

o  35.6 

Means 
Index  Corr.,  &c. 

it 
Refraction 
Parallax 

2  Altitude. 

Chronometer. 

Means. 
Index  Corr.,  &c. 

a 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

36     o     o 
35  50    o 
40    o 
36  30    o 

20      0 
10      0 

h.  m.      s. 

i  37  40.0 

38  20.5 
38  59.  o 
39  57-0 
40  36.0 
4i  15-5 

o        /          n 

34  50     o 
40    o 
30    o 
35  20    o 

IO      O 
0      O 

h.  m.      s. 
i  42  14.0 

42  53-0 
43  32.0 
44  29.0 
45     6.0 
45  45-0 

36     5     o.o 
43.0 

I  39  28.0 

34  55     o.o 
35.6 

i  43  59-8 

0               /                   // 

.  113  17  33.5 

h.  m.     s. 
2  46  49.3 

—     4  36.6 

c                 /                    ,1 

•    "3   17  34-1 

h.  m.     s. 
2  51  20.1 

36    4  17.0 
2  53.6 
+                 8.6 

34  54  24.4 
2  59.6 
4-                 8.6 

Polar  Distance  of 

L<5cal  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronomi 

Chronometer  slow 
These  observatior 

Object      .     . 

me 

Polar  Distance  of 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatioi 

Dbject       .      . 
me      ... 

2   42    12.7 

;ter 
of  Local  M.  T. 

i  39  28.0 

-ter 
of  Local  M.  T. 

i  43  59.8 

I      2   44.7 

.        I     2  43.8 

is  were  made  after  noon. 

is  were  made  after  noon. 

96 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


ADDENDUM  A— Continued. 


SUN       .         .         .         DECEMBER  15. 

SUN       .         .         .         DECEMBER  16. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc=u. 

Off  Arc  =  ui. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc=w. 

Oil'  A  re  =  <•>'." 

/      // 
33  20 
15 

20 

359  28  10 
o 
o 

33  20 

20 

15 

359  28  10 

10 
IO 

o  40.8 
+                4-9 

0  44-2 
+                 4-1 

o  35-9 

o  40.1 

Means 
Index  Corr,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

a 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

33    o    o 
32  50    o 
40    o 
33  30    o 
20    o 

IO      O 

h.  m.      s. 
i  49  13-5 
49  5i-o 
50  29.0 
51  24.0 

52      2.0 

52    38.5 

29    o    o 

IO      O 
20      0 

28  30    o 
40    o 
50    o 

h.  m        s. 

7  3S     8.5 

38  43-5 
39  19-0 

40    12.0 

40  47-5 
41   23.0 

33     5    o.o 
35-9 

I    50   56.3 

28  55    o.o 
40.1 

7  39  45-6 

0 

Ther.    63. 

in. 
Bar.       30.25 

113  17  34.9 

h.  m.     s. 

2  58  16.8 

-     4  36-3 

113  i9'4i-7 

h.  m.      s. 
8  46  44.1 

-     4  14.7 

33     4  24.1 
3     9-9 
+                8.6 

28  54  19-9 
3  33.  8 
+                8.7 

Polar  Distance  of  I 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatioi 

Dbject      .      . 
me 

Polar  Distance  of  < 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronorm 

Chronometer  slow 
These  observatior 

Object 
me 

2  53  40.5 
I   50  56.3 

8  42  29.4 
7  39  45-6 

;ter     . 
of  Local  M.T. 

•ter     .     .     . 
of  Local  M.T. 

I     2  44/2 

.        I     2  43.8 

is  were  made  after  noon. 

s  were  made  before  noon. 

REPORT  OF  PROFESSOR  HARKNESS. 


97 


ADDENDUM  A— Continued. 


SUN      .         .         .         DECEMBER  16. 

SUN       .         .         .         DECEMBER  16. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  «. 

Off  Arc  =  u'. 

Index  Corr. 

E 

Index  Corr.,  &c. 

On  Arc  =  u. 

Off  Arc  =  ui. 

33     o 

0 

10 

359  27  4° 
40 
40 

32  50 

55 
50 

359  27  45 
28    o 
27  50 

0    21.6 

+                 4-3 

o  21.7 
+                 4-6 

0    17.3 

o  17.1 

Means 
Index  Corr.,  &c. 

n 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

30  10     o 
20     0 
30     o 
2g  40     o 
50     o 
30    o    o 

h.  m.     s. 

7  42  17-5 
42  53-o 
43  29.5 
44  23.0 
44  59-0 
45  34-5 

32     o    o 
10    o 
20    o 
31  30    o 

40    o 

50      0 

h.  m.     s. 

7  48  54-5 
49  33-0 
50     9.5 
5i     5-5 
51  4L5 
52  18.5 

30     5     o.o 
17-3 

7  43  56-1 

31  55     o.o 
17.1 

7  50  37-1 

0                 /                   I/ 

,  113  19  42.1 

h.  m.     s. 
8  50  56.0 

Ther.      61. 
in. 
Bar.       30.25 

.    113  19  42.9 

h.  m.     s. 

•       8  57  36.9 

30    4  42.7 
3  3°-2 

+                 8.7 

3i  54  42.9 
3  '7-9 
+                8.7 

Polar  Distance  of 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  obscrvatio 

Object      .      . 
me 

;  Polar  Distance  of 

Local  Apparent  T 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatio 

Object      .     . 
me 

8  46  di  j. 

8    $1    22    J. 

eter 
of  Local  M.  T. 

7  43  56.1 

eter 
of  Local  M.  T. 

•       7  50  37-1 

I     2  45  3 

i     2  45.3 

is  were  made  before  noon. 

ns  were  made  before  noon. 

13— E 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


ADDENDUM  A— Continued. 


SUN       .         .         .         DECEMBER  16. 

SUN      .         .         .         DECEMBER  16. 

Index  Corr. 
E 

Index  Corr,  &c. 

On  Arc  =  u. 

Off  Arc  =  u'. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  u. 

Off  A  re  =  <•)'. 

33     o 
32  55 
33     o 

359  27  40 
40 
40 

32  55 
50 

55 

359  27  50 
50 
45 

o  19.2 
+                 4-6 

O   2O.8 

+                 4-4 

o  14.6 

o  16.4 

Means 
Index  Corr.,  &c. 

it 
Refraction 
Parallax 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

U 
Refraction 
Parallax 

2  Altitude. 

Chronometer. 

31  40     o 
30    o 

20      0 

32  10    o 
o    o 
31  50    o 

h.  m.     s. 
I   54  23.5 
55     o.o 
55  37.o 
56  31.0 
57     7-5 
57  4.6-5 

30  30     o 
20      0 

10    o 

3100 
30  50    o 
40     o 

h.  m.     s. 
I   58  40.0 

59  17-5 
59  54-0 
2      O   47.0 
I    23.5 
I    58.0 

31  45     o.o 
14.6 

i  56    4.2 

30  35     o.o 
16.4 

2      O    2O.  O 

.    113   2O  22.6 

h.   m.     s. 
.        3     2  55.4 

4      7.O 

.     113    2O    23.O 

h.  m.     s. 

3     7  H.  = 

—     4     6.9 

31  44  45-4 
3  16-3 
+                 8.6 

30  34  43-6 
3  23.9 
+                8.7 

Polar  Distance  of 

Local  Apparent  Ti 
Equation  of  Time. 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatior 

Object 
me 

Polar  Distance  of 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  ChrononK 

Chronometer  slow 
These  observatior 

Object      .      . 
me      ... 

2    ^8   48    d 

3     3     4-3 

:tcr 
of  Local  M.  T. 

I    56      4-2 

:tcr 
of  Local  M.  T. 

2      0    20.0 

I      2   44.2 

I     2  44.3 

is  were  made  after  noon. 

is  were  made  after  noon. 

REPORT  OF   PROFESSOR  1IARKNESS. 


99 


ADDENDUM   A— Continued. 


II 

SCN       .          .          .          DECEMBER  16.                   SUN       .          .          .         DECEMBER  ig. 

Index  Con. 
E 

Index  Corr.,  iVc. 

On  Arc  =  u. 

Off  Arc  =  w'. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  u. 

Off  Arc  =  W. 

32  50 

50 
40 

359  27  40 
35 
40 

.     32  40 
3° 
50 

359  27  35 
35 
25 

o  12.5 
f                  4.1 

o     5.8 
+                 4-1 

o     8.4 

o     1.7 

Means 
Index  Corr.,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

28  30     o 
20    o 

IO      O 

29    o    o 
28  50    o 
40    o 

h.  m.     s. 

2     5  52.0 
6  27.5 
7     2.5 
7  55-0 
8  31.0 
g     6.0 

0            1            It 

29  10    o 
20    o 
30    o 
28  40    o 
50    o 
29    o    o 

h.  m.      s. 
7  40  44.5 
41  20.5 
41   56.0 
42  49.0 
43  25.5 
44     i.o 

28  35     o.o 
8.4 

2     7  29.0 

29     5     o.o 
.1.7 

7  42  22.8 

Ther.     67. 

in. 
Bar.       30.18 

113  20  23.9 

h.  m.     s. 
3  14  21.  o  i 

4     6.8 

113  25  36.8 

h.  m.     s. 

8  47  54.8 

2  45.9 

28  34  51.6 

3  38.3 
+                 8.7 

29    4  53.3 
3  40.6 
+                8.7 

Polar'Distance  of  C 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronome 

Chronometer  slow 
These  observation 

)bject 
me      .... 

Polar  Distance  of  ( 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronome 

Chronometer  slow  < 
These  observation 

Jbject 
me     ... 

3  10  14.2 
2     7  29.0 

S  45     8-9 
7  42  22.8 

ter     .     .      .      . 

jf  Local  M  .  T.  . 

ter     ... 

jf  Local  M.T.   . 

I     2  45.2 

I       2    46.1 

s  were  made  after  noon. 

s  were  made  before  noon. 

100 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


ADDENDUM  A— Continued. 


SUN       .         .         .         DECEMBER  19. 

SUN      .         .         .         DECEMBER  19. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  w. 

Off  Arc  =  u1. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc=w. 

Oil'  Arc=u>. 

33     o 

0 
IO 

359  27  5° 
45 
45 

33-  o 

0 

o 

359  27  45 
30 
40 

o  25.0 

+                4-3 

o  19.2 

+                4-7 

o  20.7 

0    14-5 

Means 
Index  Corr.,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

30  20    o 
30    o 
40    o 
30    o    o 

IO     O 

20      O 

h.  m.      s. 
7  44  54-5 
45  29.5 
46     5-5 
47  38-0 
48  13-5 
48  49  '.5 

32  30    o 
40    o 
50    o 
32     o    b 

10      O 

20    o 

h.  m.      s. 

7  52  49-5 
53  24.0 
54     5-0 
54  59-5 
55  37-0 
56  12.5 

30   20      O.O 
^-                   2O.7 

7  46  51.8 

32  25     o.o 

0    14-5 

7  54  3L2 

.   113  25  37.1 

h.  m.     s. 
8  52  23.4 

2   45.8 

Ther.       53. 

in. 
Bar.       30.20 

.    113  25  37.4 

h.  m.     s. 
.       9     0     3.1 

—    2  45  .  6 

3°  19  39-3 
3  3i-4 
+                8.7- 

32  24  45.5 
3  17.6 
+                8.6 

Polar  Distance  of 

Local  Apparent  Ti 
Equation  of  Time. 

Local  Mean  Time 
Time  by  Chronorm 

Chronometer  slow 
These  observatior 

Object      .     . 
me      ... 

Polar  Distance  of  Object     . 

Local  Apparent  Time 
Equation  of  Time  

Local  Mean  Time  

8  49  37.6 

8  57  17  q 

;ter 
of  Local  M.  T. 

7  46  5.1.8 

Time  by  Chronometer 
Chronometer  slow  of  Local  M.  T. 

7  54  31-2 

I     2  45.8 

I      2    46.3 

s  were  made  before  noon. 

These  observations  were  made  before  noon. 

REPORT  OF  PROFESSOR  HARKNESS. 


101 


ADDENDUM  A — Continued. 


SUN       .         .         .         DECEMBER  ig. 

SUN       .         .         .         DECEMBER  19. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  a. 

Off  Arc  =  u'. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  u. 

Off  Arc  =«'. 

33  15 

0 

o 

359  27  50 
28     o 

27  45 

32  40 
33    o 
o 

359  27  45 
45 
40 

o  28.4 
+            4.6 

o  18.3 
+                 4'-4 

—        o  23.8 

o  13.9 

Means 
Index  Corr.,  &c. 

a 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

a 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

31   20    o 
10    o 

0      0 

31  50    o 
40    o 
30    o 

h.  m.     s. 
I   56  33.0 

57  M-5 
57  46-0 
58  41.0 
50  18.5 
59  54-5 

30  10    o 
o    o 
29  50    o 
30  40    o 
30    o 

20      0 

h.   m.    s. 
2      0  49.5 
I    27.0 

•      2     3-5 

2    56.0 
3  32.0 
4     g.o 

31  25     o.o 

23.8 

I   58  14.6 

30  15    o.o 

13-9 

2      2   29.5 

"3  25  55.7 

h.  m.    s. 
3     3  37-1 

2  38.1 

113  25  55-9 

h.  m.    s. 
3     7  52.0 

—     2  38.0 

31  24  36.2 

3  20.8 
+.                8.6 

30    14    46.1 

3  28.6 
+                8.7 

Polar  Distance  of 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatioi 

Object    . 
me     .... 

Polar  Distance  of 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatiot 

Object    .      .      . 
me     .... 

3     o  59-0 
I   58   14.6 

3     5  M.o 

2      2   29.5 

^ter    .... 
of  Local  M.T.  . 

:ter    .... 
of  Local  M.  T.  . 

I      2   44.4 

I       2    44.5 

is  were  made  after  noon. 

is  were  made  after  noon. 

1O2 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


ADDENDUM  A— Continued, 


SUN       .         .         .         DECEMBER  ig. 

SUN       .         .         .         DECEMBER  21. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  u. 

Off  Arc  =  w>. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  ". 

Off  Arc  =  u'. 

*      n 

33  15 
10 
o 

359  27  45 
50 
40 

33     o 

0 

o 

359  27  40 
30 
40 

o  26.6 

+              4.0 

o  18.4 

+           3.7 

O   22.6 

o  14.7 

Means 
Index  Corr.,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

28  20    o 

IO      0 
O     0 

28  50    o 
40    o 
30    o 

h.    m.     s. 
2     7  27.0 

8      2.0 

8  38.0 
9  30.0 
10    6.0 
10  41.5 

26  30    o 
40    o 
50    o 
26    o    o 

IO      0 

20    o 

h.  in.      s. 
7  32  34-0 
33     7-5 
33  41-5 
34  34-5 
35     9-5 
35  43-5 

28  25    o.o 

22.6 

2     9    4.1 

26  25    o.o 

14.7 

7  34     8.4 

Ther.     60. 

in. 
Bar.       30.12 

113  25  56.2 

h.  m.     s. 
3   14  26.7 

-     2  37-9 

113  27   12.4 

h.  in.     s. 
8  38  39.9 

—      I  46.1 

28  24  37.4 

3  42.2 

+          8.7 

26  24  45.3 

3  55-i 
+                8.8 

Polar  Distance  of 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observation; 

Object    .      .      . 
me    .... 

Polar  Distance  of 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronomt 

Chronometer  slow 
These  observations 

3bject    .      .      . 
me    .... 

3  II  43.8 
2      9'    4.1 

8  36  53-8 
7  34     8.4 

iter    .... 
of  Local  M.T.  . 

•ter    .... 
of  Local  M.T.  . 

I      2   44.7 

I     2  45.4 

,  were  made  after  noon. 

were  made  before  noon. 

REPORT  OF  PROFESSOR  1IARKNESS. 


103 


ADDENDUM  A— Continued. 


SUN       .         .        „         DECEMBER  21. 

SUN      .         .         .         DECEMBER  21. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  u. 

Off  Arc  =  w>. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  a. 

Off  Arc=«>. 

32  30 
40 
40 

359  27  30 
40 
30 

32  40 
50 
40 

359  27  30 
25 
40 

o     5.0 
+                 3-9 

o     7-5 
+                4.2 

O      I.I 

-         .0    3-3 

Means 
Indi-x  Corr.,  £c. 

n 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

n 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

27  40     o 
50    o 

28     o    o 

2f   IO      O 
20      O 

30    o 

h.  m.      s. 
7  36  37-0 
37  II.  o 

37  46-5 
38  39-0 
39  13.5 
39  49^ 

0              /                It 

29  30    o 
40    o 
50    o 
29     o    o 

IO      0 
20      O 

h.  m.      s. 

7  43     4-0 
43  39-5 
44  15.5 
45   IT.O 
45  47.0 
46   22.  O 

27  35     o.o 
i.i 

7  3S  12.7 

29  25     o.o 
3-3 

7  44  43-2 

.    113  27  12.4 

h.  m.     s. 

8  42  45.4 

—     i  46  o 

Ther.      64. 
in. 
Bar.       29.86 

0                /                    tl 

.    113  27  12.5 

h.  m.     s. 
8  49  16.1 

27  34  53-9 
3  45-2 
+                 8.7 

29  24  56.7 

3  3i.o 
+                8.7 

Polar  Distance  of 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronomc 

Chronometer  slow 
These  observation 

Object      .      . 
me      ... 

Polar  Distance  of  ( 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronomc 

Chronometer  slow 
These  observation 

Dbject      .     . 
me 

8    dO    t,Q   A 

.        8  47  30.2 
7  44  43-2 

ter 
of  Local  M.  T. 

7  38  12.7 

'ter     . 
of  Local  M.  T. 

I     2_4&.7 

I     2  47.0 

s  were  made  before  noon. 

s  were  made  before  noon. 

104 


OBSERVATIONS  OF  THE.  ECLIPSE  OF  DECEMBER  22,  1870. 


ADDENDUM  A— Continued. 


SUN       .         .         .         DECEMBER  21. 

SUN       .         .         .         DECEMBER  21. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  ". 

OffArc=<J>. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc=u. 

Off  A  re  =<•>'. 

33     o 
10 
o 

359  27  40 
30 
40 

o  20.  o 
+                4-6 

o  24.6 
+                4-4 

o  15.4 

O   20.  2 

Means 
Index  Corr,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

n 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

31  20    o 

IO     0 

o    o 

31  5°    o 
40    o 
30    o 

h.  m.      s. 
i  57  24.5 

58     i.o 
58  38.0 
59  33-0 

2      O      g.O 

o  46.0 

30  ii     o 

29  58  10 

50  20 

30^44   20 

36  10 

25    50 

h.  m        s. 

2      I    3S.5 
2    25.0 

2  53-0 
3  33-0 
4     3-0 
4  39-5 

31  25     o.o 

15.4 

i  59     5-2 

30    IT"  38.3 
20.2 

2       3    12.  O 

.    113  27  16.6 

h.  m.     s. 
3     3  28.2 

—     i  38  i 

.    113  27  16.6 

h.  m.      s. 
3     7  34-5 

-     i  38.0 

31  24  44.6 

3  16.1 

+                 8.6 

30  17  iS.i 
3  23.6 
+                8.7 

Polar  Distance  of 

Local  Apparent  T 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatio 

Dbject      .     . 
me 

Polar  Distance  of 

Local  Apparent  Ti 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatioi 

3bject      .     . 
me 

-3        I     CQ    I 

3     5  56.5 

cter     . 
of  Local  M.T. 

i  59     5-2 

:tcr     . 
of  Local  M.T. 

2     3  12.0 

I      2   44.9 

I      2   44.5 

is  were  made  after  noon. 

is  were  made  after  noon. 

REPORT  OF  PROFESSOR  HARKNESS. 


'05 


ADDENDUM   A— Continued. 


SUN       .          .          .          DECEMBER   21. 

SUN       .         .         .         DECEMBER  22. 

Index  Corr. 
E 

Index  Corr.,  &.c. 

On  A  re  =6>. 

Off  Arc  =  (Ji. 

On  Arc=w. 

Off  Arc  =  u'-. 

33  25 

25 

20 

359  27  30 
4° 
35 

33  15 
o 
o 

359  27  40 
35 
30 

0    29.2 

+                  4-1 

Index  Corr.                           o  20.0 
E                               +.              3.7 

o  25.1 

Index  Corr.,  &c.                 o  16.3 

Means 

Index  Corr.,  &c. 

Q 
Refraction 
Parallax 

2  Altitude. 

Chronometer. 

2  Altitude. 

Chronometer. 

29     4  30 
28  52  40 

33  5° 
29  26  20 
3  10 
28  54  20 

h.  m.       s. 
2     5  38-0 
6  24-5 
7  23-5 
8   13-5 
9  36.5 
10     6.5 

26  40    o 
50    o 
27     o    o 
26  10    o 
20    o 
30    o 

h.    m.     s. 

7  33  38.0 

34  12.5 
34  48-0 
35  39-5 
36  14.0 

36-49-5 

'28  59     8.3 

2     7  54-  f> 

Means                            26  35     o.o 
Index  Corr.,  &c.                       16.3 

7  35   13-0 

25.1 

O 

Ther.     64.6 

in. 
Bar.       29.70 

.    113  27   16.7 

h.    in.     s. 
3  12  17.2 

•      -     I   37-9 

.    113  27   18.0 

h.  m.     s. 
8  39  15.2 

28  58  43.2 
3  32.8 
+                 8.7 

a                                      26  34  43.7 
Refraction                              3  54.8 
Parallax                    +                 8.8 

Polar  Distance  of 

Local  Apparent  T 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatio 

Object 
me     ... 

Polar  Distance  of  Object 
Local  Apparent  Time 

.       3   10  39-3 
2     7  54.6 

8  37  59-2 
7  35   13-6 

eter     . 
of  Local  M.T. 

Time  by  Chronometer     . 

I       2    44.7 

Chronometer  slow  of  Local  M.T.  .       i     2  45.6 
These  observations  were  made  before  noon. 

is  were  made  after  noon. 

14— E 


io6 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


ADDENDUM  A— Continued. 


SUN      .         .         .         DECEMBER  22. 

SUN      .         .         .         DECEMBER  22. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  u. 

Off  Arc  =  u'. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  A  re  =  o. 

Off  Arc  =  u>. 

32  So 
33  15 

10 

359  27  45 
45 
28     o 

32  5° 
33   15 

10 

0            1               II 

359  27  40 
40 
40 

o  27.5 
+                3-9 

o.  22.5 

+                 4-2 

o  23.6 

o  18.3 

Means 
Index  Corr.,  &c. 

Q 

Refraction 
Parallax 

2  Altitude. 

Chronometer. 

• 

Means 
Index  Corr.,  &c. 

0 
Refraction 
Parallax 

2  Altitude. 

Chronometer. 

27  50    o 
28     o    o 

IO      0 

27  20    o 
30    o 
40    o 

h.  m.      s. 
7  37  41-5 
38  17.0 
38  Si.o 
39  45-0 
40  20.  o 
40  56.0 

29  40    o 
50    o 
30    o    o 
29  10    o 

20      0 

30    o 

h.  m.     s. 
7  44   13.0 

44  4S.5 
45  23-5 
46  18.0 
46  54.0 
47  30.0 

27  45     o.o 
23.6 

7  39  l8-4 

29  35     o.o 
18.3 

7  45   51.2 

Ther.     54.0 

in. 
Bar.       29.42 

.    113  27  17.9 

h.  m.      s. 

.       8  49  5  i  .  5 

.      —      i   15.8 

27  44  36.4 
3  44-9 
+                8.7 

29  34  41.7 
3  30-9 
+                8.7 

Polar  Distance  of 

Local  Apparent  T 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatio 

Object      .      .     .113  27  17-9 

h.  m.     s. 
me      ....       8  43  19.6 

—         T     T  K     n 

Polar  Distance  of 

Local  Apparent  T 
Equation  of  Time 

Local  Mean  Time 
Time  by  Chronom 

Chronometer  slow 
These  observatio 

Object      .      . 
me 

eter     . 
of  Local  M.  T. 

.       8  42     3.7 
7  39  lS-4 

8  48  35.7 

eter 
of  Local  M.  T. 

7  45   51-2 

.        I     2  45.3 

I     2  44.5 

ns  were  made  before  noon. 

ns  were  nude  bH'ntr  noon. 

REPORT  OF  PROFESSOR  HARKNESS. 


107 


ADDENDUM  B. 

Obsen<atiom  for  LatiluJc,  maJf  on  the  Stone  Gun-Platform  at  Syracuse,  Sicily,  by  Professor  William  Harkness, 
U.  S.  N.,  with  the  Sextant  Stackpole  <5^  Brother  No.  937,  Mercurial  Artificial  Horizon  Ha.  i,  and  Chro- 
nometer T.  S.  &  J-.  D.  Negus  No.  1115. 

[NOTE. — The  barometer  employed  was  a  pocket  aneroid,  i.g  inches  in  diameter,  marked  L.  Casella,  London,  No. 
1128.  It  was  compensated  for  temperature,  and,  in  ordei  to  reduce  its  observed  readings  to  the  corresponding  readings 
of  a  mercurial  barometer  at  32°  F.,  it  is  only  necessary  to  subtract  from  them  0.12  of  an  inch.] 


SI  \      .         .         DECEMBER  13,  1870. 

POLARIS     .          DECEMBER  14,   1870. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc=". 

Off  Arc  =  W. 

Index  Corr. 
E 

Index  Corr.,  &c. 

Coincidence 
of  Images. 

32  40 

45 
33     5 

5 

359  28    o 

27    50 

28     o 
28  10 

o  55 
45 
50 

o  26.9 

+                     10.  0 

o  50.0 

+              14-0 

o  16.9 

o  36.0 

Means 
Index  Corr.,  &c. 

il 

f 
Refraction 
Parallax 
Ama 
B*, 

c, 

S 

t 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

Q 

JQ 
Refraction 
/  cos  t 
2d  term 

t 

2  Altitude. 

Chronometer. 

59  43  50 
45   50 
44  40 
58  38  30 
34  40 
33  35 

h.  m.     s. 

ii     9  57.0 

ii  20.5 
ii  51.0 

12    34.0 

14     8.5 
14  33-5 

76  37  50 
34  30 
35  30 
35  3° 
34  30 
34     o 

h.  m.     s. 

•     8  27  19.0 
29  27.0 
31  35-0 
33  13-5 
34  19.0 

35   ii  -5 

59  ii     0.8 
i6.g 

II    12   24.1 

76  35   18.3 
36.0 

8  31   50.8 

Ther.       66.0 

in. 
Bar.      30.26 

h.  m.     s. 
It   54  22.9 

I     2  43.2 

Ther.       59.0 

in. 
Bar.      30.26 

h.    m.    s. 
i     2  43.7 

i  55  48.5 
88°  37'  28".  o 
4952".  o 

59  10  43.9 

76  34  42.3 

60  24  38.0 
+           I  39-7 

7-8 
-         ii   57-1 
+                 0.7 

38    17    21.2 
I    12.8 
I    12    13.2 
+                   II.  0 

+  37    4    6- 

Co  14  13.5 
—  23  10  10.8 

Chronometer  slow 
( 

+   37     4     3- 

Time  of  Culminat 
Chronometer  slow 

Chron.  Time  of  C 

ion  .... 

rf    

i>    . 

jlmination  . 

10  51  39.7 

io8 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


ADDENDUM   B— Continued. 


POLARIS      .         .         DECEMBER  14. 

SUN       .         .         .         DECEMBER  16. 

Index  Corr. 
E 

Index  Corr.,  &c. 

Coincidence 
of  Images. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc=<j. 

0(1'  Arc  =  u'. 

i     o 

o  55 

I       0 

33     o 

10 
0 

359  27  50 
50 
50 

o  58.3 
+              14.0 

o  26.6 

+                   10.  0 

o  44-3 

o  16.6 

• 

Means 
Index  Corr.,  &c. 

a 

ja 

Refraction 
p  co's  / 
2d  term 

f 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

Q 

c 

Refraction 
Parallax 
Am^ 

?• 

S 

</> 

2  Altitude. 

Chronometer. 

76  32  50 
33  30 
33  30 
32  10 
31  40 
3i  30 

h.  m.     s. 
8  36     1.5 
36  54.0 
37  39-0 
38  21.0 
39  26-5 
40  ig-5 

59  47  40 
47  30 
47  40 
58  42  10 
41  30 

41    20 

h.  m.     s. 

10  54  47-5 
55  38.5 
56     1.5 
57    o.o 
57  38.5 
58  16.0 

76  32  31.7 
44-3 

8  38     6.9 

59  M  3S-3 
'    16.6 

10  56  33-7 

h.   m.     s. 
I     2  43-7 

2      2      5.6 

88°  37'  28".o 
4952".o 

h.  m.     s. 
ii  55  49-3 

i     2  44.2 

76  31  47-4 

'59  14  21.7 

38   15  53-7 

I    12.8 

-      i   II     5-7 
+                   12.  1 

60   22   49.2 

+           I   39-8 
7.8 
22.3 

+   37     3  47- 

60  23  59 
—       23  20    3 

Chronometer  slow      .... 
t        

+       37     3  56 

Time  of  Culmination 
Chronometer  slow      .... 

6        

p        .     . 

Chron.  Time  of  Culmination     . 

10  53     5-i 

REPORT  OF  PROFESSOR  HARKNESS. 


IO9 


ADDENDUM   B— Continued. 


.SUN      .         .         .         DECEMBER  16. 

• 

POLARIS      .         .         DECEMBER  16. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  «. 

Off  Arc  =<Ji. 

Index  Corr. 
E 

Index  Corr.,  &c. 

Coincidence 
of  Images. 

33     o 
o 

20 

359  28  10 
27  50 
45 

'     '/ 
o  20 
30 

25 

o  30.8 

1                       10.  0 

o  25.0 

+         14-1 

0  20.8 

o  10.9 

Means 
Index  Corr.,  &c. 

Q 

c 

Refraction 
Parallax 
Ama 

fl 

6 

<t> 

2  Altitude. 

Chronometer. 

Means  ~ 
Index  Corr.,  &c. 

i.' 

iO 

Refraction 

p  COS  t 

2d  term 
<t> 

2  Altitude. 

Chronometer. 

58  41     o 
40  30 
40  15 
59  44  3° 
43  50 
43  3° 

h.  m.     s. 
10  58  50.0 

59  19-° 

59  52.5 

II      0   56.5 

i  39-5 

2      8.0 

76  48  30 
50  3° 
49  4° 
48  45 
50  10 
50  10 

h.  m.      s. 
5  27  41.0 
29  42.0 
30  50.0 
3i  55-o 
32  49-0 
33  33-5 

59  12   15.8 

ii     o  27.6 

76  49  37-5 

IO.Q 

5  31     5-i 

20.  8 

Ther.     64.5 

in. 
Bar.       30.21 

h.   m.      s. 
ii  55  49-3 

i     2  44.2 

h.  m.      s. 
i     2  44.3 

0  57  31-5 
88°  37'  28".4 
495i"-° 

59  "  55-o 

76  49  26.6 

60  24     2.5 
+           i  39-8 
7-8 
i  32-4 

38  24  43.3 

I     12.6 

-     i   19  56.5 
+                 2.9 

.    60    24      2. 

+  37     3  37- 

Chronometer  slow      .... 

e       

+  37     3  58. 

Time  of  Culmination 
Chronometer  slow      .... 

6 

t 

Chron.  Time  of  Culmination 

•     10  53    -5.0 

no 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


ADDENDUM  B— Continued. 


POLARIS      .         .         DECEMBER  16. 

SCN      .         .         .         DECEMBER  17. 

Index  Corr. 
E 

Index  Corr.,  &c. 

Coincidence 
of  Images. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  u. 

OffArc  =  '.' 

o  30 
30 
35 

33  15 
20 

359  28    o 
5 

0  31-7 

4-              14-2 

o  40.0 

+                     10.  0 

0    17-5 

o  30.0 

Means 
Index  Corr.,  &c. 

Q 

ifl 

Refraction 
p  cos  t 
2d  term 

f 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

a 

c 

Refraction 
Parallax 
Am, 

f, 

6 

0 

2  Altitude. 

Chronometer. 

0           1             It 

76  50  10 
51     o 
51  3° 
5i     o 
5i  40 
51  40 

h.  m.      s. 
5  35  40.0 
36  39.0 
.37  35-5 
38  54-o 
39  45-o 
40  53-5 

0           *             '/ 

59  42     o 
42  30 
42  4° 

58  38     5 
38     o 
38     o 

h.    m.     s. 
10  48  59.0 
50     o.o 
50  40.0 
51   50.0 
53     3-0 
53  47-o 

76  51  10.  o 

17-5 

5*38  14-5 

59  10  12.5 
30.0 

10  51  23.3 

Ther.       57.5 

in. 
Bar.      30.20 

h.  m.      s. 
i     2  44.3 

o  50  20.9 
int. 

76  50  52.5 

59    9  42.5 

38  25  26.2 

I    12.6 

—     I  20  32.6 

+                     2.2 

60  25     8.8 
4-           I   39-6 
7-8 
12.5 

4-  37     3  43- 

60  26-28. 

—    23   22    25. 

Chronometer  slow 

f 

+37     4     3- 

Time  of  Culmination 
Chronometer  slow    .... 

Chron.  Time  of  Culmination  . 

h.  m.     s. 
II   56  18.8 

I     2  44.5 

Star  covered  by  haze,  and  very  k 

10  53  34-3 

REPORT  OF  PROFESSOR  HARKNESS. 


Ill 


ADDENDUM  B— Continued. 


SI   N       .          .          .          DECEMBER  17. 

SUN       .         .         .         DECEMBER  18. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  w. 

OfTarc  =  ^. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  u. 

Off  Arc  =  u'. 

33     o 

10 

359  27  4° 
40 

/      a 
33    o 
o 

10 

359  27  45 
40 
35 

o  22.5 

•+-                   IO.O 

0   21.6 
+                     IO.O 

o  12.5 

o  ii.  6 

Means 
Index  Corr.,  &c. 

0 

; 

Refraction 
Parallax 
Ama 

f, 

6 

<A 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

S2 

C 
Refraction 
Parallax 
Am, 

f, 
t 

" 

2  Altitude. 

Chronometer. 

58  38     o 
38     5 
37  35 
59  42  45 
42  10 
41  30 

h.  m.    s. 
10  54  41.0 
55   18.0 
56     5.0 
57     3-0 
57  52.0 
58  45-0 

59  39  10 
39    o 
39  10 
58  34     o 
33  35 
33  35 

h.  rp.      s. 
10  53  32.0 

54     7-5 
54  33-5 
55   io.o 
55  40-5 
56     4.0 

59  10     o.S 

12.5 

10  56  37.3 

59     6  25.0 
II.  6 

10  54  51.2 

Ther.     65. 

in. 
Bar.       30.16 

h.  m.      s. 
.      II   56  18.8 

I      2  44  .  5 

h.  m.     s. 

.      ii   56  48.4 

I      2   44   Q 

59     9  48.3 

59     6  13.4 

60  25     5.8 

+           I  39-6 
7.8 
18.7 

60  26  53.3 

+           I  38.5 
7.8 
2-3 

60  26  19. 

—    23    22    26. 

60  28   22. 

—    23   24    2O. 

+   37     3  53- 

+   37     4     2. 

Time  of  Culminat 
Chronometer  slow 

Chron.  Time  of  Ci 

on       ... 

Time  of  Culminat 
Chronometer  slow 

Chron.  Time  of  Ci 
Observations  ta_kc 

on       ... 

ilmination 

.      10  53  34.3 

ilmination      .      .      IO  54     3.5 
•n  through  clouds. 

112 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


ADDENDUM  B— Continued. 


SUN      .         .         .         DECEMBER  18. 

SUN       .         .         .         DECEMBER  19. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  u. 

Off  Arc  =  w'. 

33     o 

10 

20 

359  27  50 
45 
45 

o  28.4 

+                   IO.O 

o  18.4 

Means 
Index  Corr.,  &c. 

il 

f 
Refraction 
Parallax 

Ama 

f, 
g 

" 

2  Altitude. 

Chronometer. 

Means 
Index  Corr  ,  &c. 

Q 

f 
Refraction 
Parallax 

Am0 

f, 

S 

<f 

2  Altitude. 

Chronometer. 

58  33  3° 
33  25 
33  20 
59  38     o 
37  30 
36  50 

h.  m.     s. 
10  56  33.0 

57     6-0 
57  29.0 
58     7-0 
59  10.0 

II      0      6.5 

59  33  20 
34     o 
34  50 
58  30  10 
30  20 
30  45 

h.   in.      s. 
10  46  44.0 

47  38.0 
48  34-0 
49  30.0 
50  13.0 
50  53-0 

59     5  25.8 
u.  6 

10  58     5.2 

59     2  14.2 

- 

10  48  55.3 

Ther.       70. 

in. 
Bar.       30.07 

h.   m.      s. 
.     u  56  48.4 

I      2   44.9 

h.    m.     s. 

.      II   57  18.1 

59     5   14-2 

59     I   55-8 

60  27  22.9 
+           I  38.5 
7-8 
29.2 

60   29      2.1 
+              I    40.1 
7-8 
55.8 

60  28  24. 
-    23    24   21. 

60  29  39. 
-  23  25  47. 

+   37     4     3- 

+   37     3  52.   • 

Time  of  Culmination 
Chronometer  slow      .... 

Time  of  Culminat 
Chronometer  slow 

Chron.  Time  of  Ci 

on       ... 

Imination 

Chron.  Time  of  Culmination     .      .     10  54    3.5 
Observations  taken  through  clouds. 

.      10  54  32.9 

REPORT  OF  PROFESSOR  IIARKNESS. 


ADDENDUM  B— Continued. 


SUN                         .     '    DECEMBER  19. 

POLARIS      .         .         DECEMBER  19. 

Index  Con. 
E 

Index  Corr.,  fie. 

On  Arc  =  «. 

Off  Arc=u1. 

Index  Corr. 
E 

Index  Corr.,  &c. 

Coincidence 
of  Images. 

33  15 

10 

15 

0         I         n 

359  27  30 
30 
30 

o  30 
30 
50 

—              O   21.6 

+                     10.  0 

o  36.7 
+              14-2 

o  II.  6 

o  22.5 

Means 
Index  Corr.,  <Xc. 

Q 

; 

Refraction 
Parallax 
Ama 

fi 
A 

t> 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

Q 

W 
Refraction 
/  cos  t 
2d  term 

1> 

2  Altitude. 

Chronometer. 

58  3°  5° 
.3°  45 
31  10 
59  36  15 
36  15 
36  20 

h.  m.     s. 
10  51  35.0 

52  27.0 
53     7-0 
54  37-0 
56  16.0 
57     3-0 

0         ;        n 

76  54  30 
55  30 
55  30 
55  10 
55  10 
55  40 

h.  in.     s. 
6  29  37.5 

30  46.5 
31  48.0 

33     5-5 
35  23.5 
36  13.0 

59     3  35-3 
o  II  .6 

10  54  10.7 

76  55  i5-o 
22.5 

6  32  49.0 

Ther.       64. 

in. 
Bar.       30.16 

h.  m.      s. 
.      II   57  18.1 

I     2  45  .  2 

h.  m.     s. 

I      2   4^    ^ 

59     3  24.2 

76  54  52.5 

60  28  17.9 
+           I  40.1 
7.8 
6.7 

38  27  26.2 
i  13.5 

—      I    22    18.7 
+                     O.2 

60  29  44. 

-  23  25  47. 

+  37     3  54- 

Chronometer  slow 
/        .      .      .      .  ' 
rf 

+   37     3  57- 

o  16  15.3 
83°  37'  28".  9 
4951".! 

Time  of  Culminat 
Chronometer  slow 

Chron.  Time  of  C 

on        ... 

/        

almination 

.     10  54  32.9 

15 — E 


OBSERVATIONS  OF  THE  ECLIPSE  OF   DECEMBER  22,  1870. 


ADDENDUM  B— Continued. 


POLARIS      .         .         DECEMBER  19. 

SUN       .         .         .         DECEMBER  21. 

Coincidence 
of  Images. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc  =  w. 

Off  Arc  =  (.)'. 

- 

/     /* 
o  20 
40 
20 

'      '/ 
33  20. 
.  15 

20 

359  27  40 
30 

35 

Index  Corr. 

/ 
E 

Index  Corr.,  &c. 

Means 
Index  Corr.,  &c. 

Q 

*Q 

Refraction 
/  cos  t 
2d  term 

t> 

o  26.7 

-f           14-2 

o  26.6 
4-               10.  o 

o  12.5 

o  16.6 

2  Altitude. 

Chronometer. 

Means 
Index  Corr.,  &c. 

Q 

f 
Refraction 
Parallax 
Ama 

C, 
6 

" 

2  Altitude. 

Chronometer. 

o         ;         // 

76  55  30 
56  10 
54    o 
55     ° 
54    o 
55  10 

h.  m.     s. 
6  37  10.5 

39    4-o 
40    2.5 
41  16.5 
43     7-5 
45  45-5 

59  32  30 
32  30 
32  40 
58  27  35 
26  10 
25  55 

h.  m.     s. 
10  51  37.0 

52      2.0 

53  23.0 
59     8.5 
ii     i  38.0 

i  58.5 

76  54  58.3 
12.5 

6  41     4.4 

58  59  33-3 
16.6 

58  59  i6-7 

10  56  37.8 

Ther.      49.5 

in. 
Bar.      30.  13 

h.  m.     s. 
ii  58  18.1 

i     24^.0 

76  54  45-8 

38  27  22.9 
I  13.5 

—      I    22      2.8 
+               0.5 

60  30  21.6. 

+           i  38.3 
7.8 

34-1 

+37     4     7- 

60  31  18. 

—    2^    27    1=; 

Chronometer  slow 
f 

h.  m.     s. 

r                   .      .      -        T      i  AC.  .  ^ 

+  37    4     3- 

o  24  32.0 

;  Time  of  Culmina 
Chronometer  slo\ 

Chron.  Time  of  C 

ion 

' 

ulmination    . 

10  55  32.2 

REPORT  OF  PROFESSOR  HARKNESS. 


ADDENDUM  B-Continued. 


SUN       .         .         .         DECEMBER  21. 

Index  Corr. 
E 

Index  Corr.,  &c. 

On  Arc=w. 

Off  Arc=6j>. 

33  10 
15 
15 

359  27  50 
40 
45 

o  29.2 

+                     10.  0 

o  lg.2 

Means 
Index  Corr.,  &c. 

Q 

f 

Refraction 
Paralbx 

Am 

fl 

,5 

9 

2  Altitude. 

Chronometer. 

58  25  10 
25     o 

24  50 

59  29  10 
28  30 
27  40 

,     h.    in.     s. 

II       2    38.5 

3     0.5 
3  25.5 
4  25.0 
5     o.o 
5  29.0 

58  56  43-3 
—        •       19.2 

ii     3  59-8 

Ther.     67.0 

in. 
Bar.       29.77 

58  56  24.1 

60  31  48.0 

+           I  33.5 

7.8 

2      O.O 

60   31    ig. 

-  23  27  15. 

+  37     4     4- 

Time  of  Culminat 
Chronometer  slow 

Chron.  Time  of  C 

h.  m.     s. 
ion       .      .      .            ii  58  18.1 

I        2    4S.O 

ulmination 

.     TO  55  32.2 

n6 


OBSERVATION'S  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


ADDENDUM  C. 

• 

List  of  Articles  forming  part  of  the  Equipment  of  the  Expedition  to 


i  Achromatic  Telescope  of  3  inches  aperture  and  43! 
inches  focus,  equatorially  mounted,  and  provided 
with  the  necessary  eye-pieces,  shade-glasses,  dew- 
cap,  caps  for  reducing  aperture  of  object-glass, 
counterpoises,  adjusting  tools,  &c. 

I  Single-Prism  Spectroscope,  with  an  adapter  for  attach- 
ing it  to  the  telescope,  shade-glasses  for  observing 
spectrum  of  the  sun,  and  a  lantern  for  illuminating 
the  micrometer  scale. 

I  Arago  Polariscope  of  double  rotation,  for  use  in  the 
hand. 

i  Arago  Polariscope,  and  I  Savart  Polariscope, fitted  for 
use  with  a  telescope. 

i  Six-inch  Sextant,  having  a  thermometer  packed  in  the 
same  case  with  it. 

i  Mercurial  Artificial  Horizon. 

i  Pocket  Sextant. 

i  Black-glass  Artificial  Horizon,  provided  with  inclined 
planes  for  measuring  zenith  distances  up  to  130°. 

i  Prismatic  Compass. 

1  Small  Reflecting  Level. 

2  Pocket  Compasses. 

i  so-foot  Tape-Measure. 

i  Binocular  Field-Glass. 

i  Pocket  Telescope,  and  screw-clip  for  same. 

i  Set  of  Colored  Glasses. 

1  Pocket  Aneroid  Barometer. 

2  Pocl?et  Thermometers, 
i  Rain-Gauge. 

i  Set  of  Drawing  Instruments. 

4  Menu-time  Box  Chronometers. 

i  Leather  Case,  with  strap,  to  carry  a  box  chronometer 

removed  from  its  gimbals. 

i  Box,  with  lock  and  leather  strap,  to  carry  4  box  chro- 
nometers removed  from  their  gimbals. 

Pig  lead,  to  be  used  for  counterpoising  telescope. 

Olive  oil  for  lubricating  axes  of  stand  for  same. 

Soft  rags  and  camel's  hair  dusting  brush  for  cleaning 

lenses, 
i  Lantern,  and  ball  of  wick  for  same. 

Burning-fluid  for  same,  composed  of  I  volume  of  spirits 
of  turpentine  mixed  with  4  volumes  of  alcohol. 

Candles  and  candlesticks. 
I  Camp-stool. 

Twine— coarse,  medium,  and  fine. 

Rope. 

Wrapping  paper, 
i  7-foot  American  boat  ensign,  and  halyards  for  same. 

Crelle's  Rechentafeln. 


Bremikcr's  6-Figure  Logarithms. 
Bowditch's  5-Figure  Logarithms. 
4-Figure  Logarithms. 
Loomis's  Practical  Astronomy. 
Chauvenet's  Spherical  aud  Practical  Astronomy. 
Chauvenet's  Trigonometry. 
American  Nautical  Almanac  for  1870. 
English  Nautical  Almanac  Circular,  No.  12,  giving  path 
of  the  total  solar  eclipse  of  December  21-22,  1870. 
Celestial  Atlas. 

Scale  of  tints  for  comparison  with  color  of  prominences. 
!  English  Admiralty  Charts  : 
North  Coast  of  Sicily. 
East  Coast  of  Sicily. 
Southern  Coast  of  Sicily. 
Sardinia  to  Malta,  including  Sicily. 
Malta  and  Gozo  Islands. 
Valetta  Harbors,  and  the  Coast  Westward  to  Mada- 

lena  Point. 
Syracuse  Harbor. 
City  and  Bay  of  Palermo. 

Blank  forms  for  time,  latitude,  and  spectroscope  obser- 
vations. 

Foolscap,  letter,  and  note-  paper. 
Drawing  and  tracing  paper. 
Buff-colored  paper. 
Blotting  paper. 
Envelopes,  assorted  sixes. 
Ink. 

Pens  and  penholders. 
Black  lead  pencils. 
Blue  and  red  pencils. 
India  rubber. 
Paper-cutter. 
Sealing-wax  and  wafers, 
i  Small  drawing  board,  ruler,  and  squaie. 
i  Claw-hammer. 
i  Hatchet. 
i  Brace  and  bits. 
3  Screw-drivers,  assorted  sixes. 
i  Set  of  awls,  and  other  small  tools,  contained  in  a  hollow 

handle. 

i  Pair  flat  pliers, 
i  Pair  round  pliers. 
I  Pair  cutting  pliers. 
Sail-needles.' 

Screws  and  nails,  assorted  sixes. 
Wire  of  assorted  sixes. 
6  sheets  of  sand  and  emery  l>.i|>er,  assorted. 


REPORT  OF  PROFESSOR  HARKNESS.  ll"J 

ADDENDUM    D. 

• 

Leila  of  Captain  7 liftman,  R.  M.  A.,  giring  an  Account  of  O/'tt'inifitu/s  made  by  him  on  the  Total  Solar  Eclipse  of 
December  22,  1870,  while  assisting  Professor  Harkness  at  Syracuse. 

H.  M.  S.  PRINCE  CONSORT, 

Malta,  December  27,  1870. 

MY  DEAR  PROFESSOR  HARKNESS  :  According  to  promise,  I  send  you  the  few  remarks  I  have  to  make 
concerning  the  eclipse,  so  that  you  may  know  exactly  whereabouts  I  kept  your  spectroscope  during  the 
totality. 

It  is  no  use  my  saying  anything  about  your  "finder,"  through  which  I  observed  the  corona.  If  I  give 
any  details  worth  publishing  you  can  add  a  description  of  the  instrument.  It  struck  me  when  looking  at 
the  spots  on  the  sun  that  it  was  particularly  good.* 

At  the  first  contact  the  telescope  was  steady,  and  my  time  is  good: 

When  we  were  examining  the  adjustment  of  the  pointer  of  the  finder  with  the  slit  of  the  spectroscope, 
I  kept  the  former  on  the  upper  cusp  of  the  sun's  crescent.  The  telescope  was  vibrating  too  much  in  the 
wind  to  judge  if  the  adjustment  was  very  accurate,  but  I  do  not  think  there  was  an  error  of  one  minute. 

I  am  unaware  of  the  position  in  which  the  slit  was  placed  with  respect  to  the  vertical ;  but  I  remember 
that,  facing  the  sun,  the  eye-telescope  of  the  spectroscope  was  on  the  left  and  inclined  very  little  upward, 
say  fifteen  degrees. 

J  watched  the  disappearance  of  the  sun  without  the  intervention  of  any  coloring-glass  whatever.  The 
definition  was  perfect.  The  fine  crescent  shortened  somewhat  rapidly,  then  broke  up  at  either  end  into 
several  elongated  beads  of  light,  and  finally  disappeared  with  startling  suddenness,  when  I  gave  you  the 
time-signal.  I  could  not  hear  the  beats  of  the  chronometer. 

Up  to  this  time  I  had  not  seen  anything  of  the  corona  or  protuberances,  and  I  do  not  think  the  com- 
plete disk  of  the  moon  was  visible;  however,  I  did  not  take  my  eye  off  the  disappearing  limb  of  the  sun. 
The  ring  of  prominences  and  corona  appeared  as  if  by  magic  as  the  last  ray  of  direct  sunlight  vanished. 
The  brilliancy  of  the  prominences  quite  startled  me,  especially  of  one  a  little  to  the  right  of  the  vertex. 
Their  color,  and  that  of  the  thin  ring  of  light  which  united  them,  was  a  strong  apricot  pink,  a  cplor  very 
difficult  to  match  or  describe.  It  was  quite  free  from  any  tint  of  orange  or  vermilion,  and  unlike  any  color 
of  the  solar  spectrum.  The  high  protuberances  appeared  like  electric  lights  attached  to  the  limb  of  the 
moon.  There  was  a  break  or  interruption  in  the  colored  ring  in  the  right  lower  quadrant,  some  twenty 
degrees  long,  between  two  not  very  conspicuous  prominences,  D.,  Fig.  i.'. 

The  body  of  the  moon  was  considerably  illuminated  with  a  greenish-gray  tint,  similar  to  the  luniiere 
cendree  seen  at  new  moon.     I   have  no  doubt  the  irregularities 
of  the  lunar  surface  might  have  been  seen.     The  moon  was  not 
so  dark  as  the  sky  beyond  the  corona,  of  which  I  had  an  exten- 
sive view  from  the  size  of  the  fielcl.t 

The  first  part  of  the  corona  that  attracted  my  attention  was 
a  ray,  or  enlargement  in  the  right  upper  quadrant,  a  little  to  the 
right  of  the  very  bright  protuberance  A,  (Fig.  i ;)  but  by  the  time 
you  had  done  with  the  polariscope,  which  could  hardly  have  been  ^v  ! 
ten  seconds,  the  left  and  lower  left  parts,  B  to  C,  were  the  largest  \ 
and  brightest,  and  so  they  remained  until  near  the  end  of  totality, 
when  the  part  D,  in  the  right  lower  quadrant,  almost,  if  not  quite, 
rivaled  them.  The  ray  D  did  not  enlarge  suddenly,  but  very 
gradually  indeed.  The  upper  part  of  the  corona  was  throughout 
the  faintest.  The  extreme  right  was  also  faint  until  quite  at  the  end  of  totality,  when  it  brightened  a  little 
No  part  increased  in  brilliancy  without  extending  itself  farther  from  the  moon  at  the  same  time,  so  as  to 
become  a  more  or  less  pointed  ray.  I  do  not  think  any  part  of  the  corona  extended  farther  than  twenty- 
five  minutes  from  the  limb  of  the  moon ;  no  part  was  less  than  ten  minutes,  if  so  little. 

"The  finder  attached  to  my  telescope  has  an  object-glass  of  1. 20  inches  aperture,  and  8.78  inches  focal  distance.     The  eye- 
piece used  by  Captain  Tupman  produced  a  power  of  10  diameters.     (W.  H.) 
tThe  field  of  view  was  3°  15'  in  diameter.     (W.  H.) 


n8 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


Of  the  structure  of  the  corona  I  have  the  liveliest  recollection.  It  was  made  up  entirely  of  fine  black 
lines,  (that  is,  black  enough  to  be  distinctly  visible,)  on  a  white  background,  which  qpmmenced  imperceptibly 
at  a  short  distance  from  th%  chromosphere,  and  went  off  into  the  sky  beyond.  They  were  continuous  and 
uniform,  but  unequally  distinct  and  unequally  distributed,  although  close  together  everywhere.  There  were 
no  curved  or  crossed  lines,  or  lines  radiating  from  any  other  point. 

The  corona  had  no  definite  boundary.  With  the  exception  of  the  clearly-defined  limit  of  the  red 
flame-ring  Jhere  was  no  other  line  of  demarkation  regularly  or  irregularly  parallel  to  the  moon's  limb.  It 
was  white  without  a  trace  of  any  other  color,  and  less  intense  than  a  bright  white  cloud,  except  at  the  base, 
which  was  very  bright.  The  intensity  diminished  rapidly  to  a  distance  of  five  or  six  minutes,  remained 
nearly  uniform  to  near  the  outer  limit,  then  faded  off  rather  suddenly,  although  the  unequal  extension  of 
the  different  parts  gave  it  the  appearance,  as  a  whole,  of  fading  off  much  more  gradually.  There  was  nothing 
geometric  in  its  form,  and  the  brighter  portions,  which  were  invariably  those  that  extended  the  farthest,  did 
not  appear  to  have  any  relation  of  position  with  the  prominences.  The  outer  limits  exhibited  no  corusca- 
tions, but  faded  off  in  the  same  uniform  radial  manner  all  round. 

It  is  quite  inconceivable  that  the  corona  could  have  presented  the  appearance  it  did  to  me  if  it  be  an 
atmosphere  surrounding  the  sun  to  a  distance  of  twenty-five  or  thirty  minutes.  My  impression  is  that  I  was 
looking  into  a  hollow  cylinder  of  light,  the  inner  surface  of  which  was  projected  flatly  on  the  plane  perpen- 
dicular to  the  line  of  sight  or  axis.  The  change  in  the  form  and  intensity  of  parts  of  the  corona  also 
seemed  incompatible  with  its  belonging  to  the  sun. 

I  hardly  feel  justified  in  making  a  drawing,  for,  having  concentrated  my  attention  on  keeping  the  pointer 
in  the  most  favorable  position  for  the  spectroscope  work,  I  did  not  make  any  estimations  of  angles  of  posi- 
tion, or  of  the  extent  or  relative  intensities  of  different  parts.  I  chose  the  brightest  parts,  and  remember 
whereabouts  they  were — but  not  exactly.  Besides,  my  head  was  inclined  considerably  to  my  left,  and  my 
estimation  of  the  position  of  the  vertex  may  be  considerably  in  error ;  but  I  am  certain  that  the  remarkably 
bright  protuberance  I  noticed  was  very  near  the  south  point  of  the  moon,  then  twenty-six  and  a  half 
degrees  to  the  right  of  the  vertex.  * 

You  will  remember  that  during  the  partial  phase  we  looked  for  a  line  of  brighter  light  on  the  sun  par- 
allel to  the  limb  of  the  moon.  I  once  or  twice  fancied  something  of  the  kind,  but  the  immediate  contrast 
would  account  for  it.  I  think  it  was  with  a  power  of  eighty  or  ninety,  with  fair  definition. t  I  also  atten- 
tively observed  the  cusps  and  the  limb  of  the  moon.  It  would  be  difficult  to  imagine  anything  more 
striking  than  the  extreme  sharpness  and  cleanness  with  which  the  light  was  cut  off.  The  irregularities  of  the 
lunar  surface  were  projected  very  sharply  on  the  sun,  affording  ocular  demonstration  of  the  absence  of  any 
atmosphere  on  the  moon. 

I  endeavored  to  keep  the  pointer  at  a  distance  of  eight  or  ten  minutes  from  the  ring  of  prominences ; 
but,  the  vibration  of  the  telescope  being  about  ten  minutes  on  either  side,  the  pointer  oscillated  between  the 
Fig.  2.  nmt>  of  the  moon  and  the  outer  part  of  the  corona.     I  first  placed  it  in  the 

middle  of  the  bright  part  B,  (Fig.  i,)  and  gradually  moved  it  down  to  C,  and 
eventually  on  to  D.  Once  I  moved  it  from  B  right  across  to  A;  but  as  you 
then  said  you  could  see  nothing  I  quickly  went  b,ack  to  B.  While  examin- 
ing the  part  D,  the  pointer  remained  very  steady  for  several  seconds  opposite 
the  middle  of  the  interruption  in  the  ring  of  prominences,  the  extreme  point 
making  about  an  equilateral  triangle  with  the  terminal  protuberances,  (Fig.  2.) 
Of  the  ninety-five  to  one  hundred  seconds  that  you  observed  the  spectrum 
the  pointer  was  not  ten  near  the  ring  of  prominences.  The  spectrum  of  the 
chromosphere  may  have  been  very  often  visible  when  the  silt  was  normal  to  the 
limb.  From  your  exclamations  at  the  time  I  know  that  the  outer  limit  of  the 
corona  gave  a  green  line,  and  it  seems  to  me  a  most  fortunate  circumstance 
that  the  slit  was  open  to  the  right  extent. 

The  limb  of  the  sun  re-appeared  very  suddenly,  and  I  at  once  noted  the 
time,  for  which  I  had  to  put  my  face  very  close  to  the  chronometer. 


*  Captain  Tupman  sent  me  a  colored  drawing  which  is   reproduced  in  Plate  I;  except  thai   the  sky  is  there  represented 
somewhat  lighter,  and  the  body  of  the  moon  somewhat  darker,  than  in  the  original.     (W.  II.) 
t  The  magnifying  power  was  65^  diameters.     (W.  H.) 


REPORT  OF  PROFESSOR  IIAKKMiSS.  I  19 

The  following  are  the  times  I  noted  by  Negus  1115  :* 

»  h.       ra.         b. 

First  contact -•          "     35     3° 

Disappearance  of  the  sun       .......  i-      o       9.5 

Reappearance  of  the  sun        ....  1155 

Last  contact         ....                    .                              .  not  observed. 

At  Malta  the  first  and  last  contacts  were  observed  by  M.  Barthet,  with  an  astronomical  telescope  of 
about  two  inches  aperture,  as  follows  : 

h.     m.  s. 

First  contact  o     34     «  I  Valletta  mean  time. 

Last  contact  .  .          .      3     18     50  J 

The  position  of  his  observatory  is  38  seconds  of  latitude  north,  and  0.6  second  (of  arc)  of  longitude 
west  of  "Spencer's  Monument."!  I  had  computed  the  time  of  first  contact  very  accurately  from  the  data 
in  the  British  Nautical  Almanac  as  o1'  33™  5s  for  the  Monument. 

For  Syracuse  the  predicted  time  of  the  first  contact,  computed  from  the  British  Nautical  Almanac,  was 
about  ninety-five  seconds  too  late ;  by  the  American  Ephemeris  only  four  seconds  too  late. 

For  the  beginning  of  totality,  the  British  time  was  about  twenty-one  seconds  too  early ;  the  American 
about  sixteen  seconds  too  late. 

The  duration  of  the  total  phase  was  accurately  predicted  as  one  hundred  and  six  seconds. 
For  the  last  contact  Agnello's  time,  computed  from  British  data,  was  3''  21'"  54%  and  the  observed  times 
ranged  from  3h  2im  39"  to  3U  2im  59"  Syracuse  mean  time. 
I  am,  etc., 

G.  L.  TUPMAN, 

Captain  R.  M.  A. 

*  At  the  time  of  the  eclipse  Negus  1115  was  ih  2m  45". 7  slow  of  local  mean-time.  For  a  complete  list  of  all  the  times  of 
contact  observed  at  Syracuse,  see  page  82.  (W.  H.) 

tThis,  combined  \vith  the  geographical  determinations  of  the  expedition,  gives  for  the  position  of  M.  Barthet's  observatory, 
atitude  35°  53'  37"  north,  longitude  oh  58™  4".$  east  of  Greenwich.  (W.  H.) 


REPORT 


PROFESSOR  J.   R.   EASTMAN,  U.  S.  N. 


1C— K 


REPORT  OF  PROFESSOR  J.  R.  EASTMAN,  U.  S.  N. 


UNITED  STATES  NAVAL  OBSERVATORY, 

Washington,  D..  C.,  March  i,  1871. 

COMMODORE  :  I  have  the  honor  to  present  to  you,  in  accordance  with  the  orders  of  the  Honorable 
Secretary  of  the  Navy,  the  following  report  of  my  observations  of  the  total  solar  eclipse  at  Syracuse,  Sicily, 
on  December  22,  1870. 

In  accordance  with  your  instructions  I  provided  myself  with  the  following  instruments :  A  telescope, 
equatorially  mounted,  by  Clark,  with  an  object-glass  3.25  inches  in  diameter;  an  aneroid  barometer;  dry 
and  wet  bulb  thermometers ;  an  actinometer,  a  photometer,  and  a  Savart  polariscope. 

The  above  instruments  are  the  same,  except  the  photometer  and  polariscope,  that  I  used  in  1869,  and 
are  described  in  the  Observatory  Report  of  the  Eclipse  of  August  7,  1869.  The  photometer  is  the  same  as 
described  in  that  report,  except  that  the  tube  has  been  shortened  3.5  inches,  in  order,  if  possible,  to  measure 
the  relative  amount  of  diffused  light  in  the  atmosphere  during  totality.  The  Savart  polariscope  was  loaned 
me  by  Professor  Harkness.  It  is  constructed  in  the  usual  manner  of  a  plate  of  quartz,  cut  obliquely  to  the 
axis,  and  a  plate  of  tourmaline,  but  is  mounted  in  a  cell,  and  by  means  of  an  adapter  was  made  to  fit  the 
telescope  like  an  ordinary  eye-piece.  In  London  I  completed  my  list  of  instruments  by  purchasing  a  solar 
and  maximum  and  minimum  thermometers,  which  had  been  tested  at  Kew. 

All  these  instruments,  but  the  telescope  and  polariscope,  were  a  portion  of  my  private  collection. 

In  company  with  Professors  Hall  and  Harkness,  I  left  New  York  on  the  2d  of  November,  1870,  by  the 
Cunard  steamer  China,  for  England,  where  I  was  detained  two  weeks  before  I  could  secure  passage  by 
steamer  from  Southampton  to  Malta.  At  Malta  I  was  again  delayed  by  the  failure  of  the  steamer,  on  ac- 
count of  a  storm,  in  making  her  regular  trip,  but  finally  reached  Syracuse  on  the  nth  December. 

The  Prefect  of  Syracuse  very  kindly  offered  us  our  choice  of  observing  stations,  and  we  selected  that 
bastion  of  the  city  wall,  northwest  of  the  Porta  Terra,  or  gata  toward  the  mainland.  By  the  courtesy  of 
the  Prefect  and  of  the  Commandant  of  the  Italian  troops  in  Syracuse,  we  were  allowed  the  use  of  an  artillery 
store-house  in  this  bastion  for  sheltering  our  instruments  when  not  in  use,  and  were  not  only  constantly  pro- 
vided with  a  sentinel  at  the  store-house  gate  during  our  stay  in  Syracuse,  but  Colonel  Rossi  furnished  a 
strong  guard  on  the  day  of  the  eclipse  to  prevent  our  being  annoyed  by  crowds  of  idle  wonderers  from  the 
city. 

On  unpacking  the  instruments  the  aneroid  barometer  was  found  to  be  somewhat  damaged,  probably 
owing  to  the  severe  usage  which  the  box  received  when  it  was  forced  open  by  the  customs  officers  in  Liver- 
pool. 

The  errors  of  the  barometer  were  determined  by  comparison  with  another  aneroid,  and  by  frequent  com- 
parison I  found  that  its  relative  indications  were  tolerably  reliable,  though  utterly  useless  for  absolute  deter- 
minations except  when  almost  constantly  compared  with  another  instrument. 

After  securing  a  double-roof  protection  for  the  meteorological  instruments,  I  commenced  on  December 
1 6  a  series  of  observations  to  determine  the  normal  meteorological  conditions,  as  a  standard  with  which  to 
compare  the  changes  that  might  occur  during  the  eclipse. 

I  selected  as  my  station  for  observing  the  eclipse  the  Stone  Gun-Platform,  36^  yards  south  of  the 
station  chosen  by  Professor  Harkness  for  observations  for  time.  The  meteorological  instruments  were 
stationed  about  four  yards  east  of  my  observing  station,  the  barometer  being  fifty-two  feet  above  mean  half- 
tide  in  the  harbor  of  Syracuse. 

It  may  be  interesting,  as  showing  something  of  the  climate  of  Syracuse  in  December,  to  present  the 
daily  record  of  the  observations,  which  I  have  accordingly  done  in  the  following  tables.  In  these  tables  the 


124 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


readings  of  the  barometer  have  been  corrected  only  for  error  in  scale  reading  and  for  temperature,  and  the 
proper  corrections  have  been  applied  to  the  readings  of  the  thermometers. 


Date. 

Barometer. 

Thermometers.                  Wind. 

Weather. 

Dry. 

Wet. 

Solar. 

Direction. 

Force. 

Clouds. 

Portion 
cloudy. 

1870.          h. 

in. 

0 

0 

0 

Dec.  16,       8 

29.99 

56.7 

55-7 

89.0 

SE.   .     . 

I 

Cirrus  . 

I 

9 

29.98 

54-7 

54-0 

95-5 

SE.  .     . 

I 

Cirrus   . 

I 

ii 

29.98 

64.2 

60.5 

106.8 

SE.  .     . 

i 

Clear     .     .      . 

0 

12 

29.96 

61.6 

58.7 

107.5 

SE.  .     . 

I 

Clear     .      .      . 

o 

13- 

29.95 

62.2 

59.0 

108.0 

Calm     . 

o 

Clear     .      .      . 

o 

14 

29.94 

64.4 

59.0 

108.5 

Calm     . 

0 

Clear     .      .      . 

0 

15 

29.94 

65.2 

60.0 

102.0 

Calm     . 

0 

Clear     .      .     . 

o 

16 

29.94          62.7 

57.o 

100.5 

Calm     . 

o 

Clear     .      .      . 

o 

17 

29.96         60.2 

56.0 

63.O 

Calm     . 

0 

Clear     .      .      . 

0 

18 

29.96          57.2 

55-0 

55-o 

Calm     . 

0 

Stratus  .      .      . 

I 

'9 

30.00          57.2 

53-o 

55-0 

Calm     . 

o 

Stratus  . 

I 

Maximum,  66°.8.                         Minimum,  46°.8. 

Dec.  17,       8 

30.02 

50.5 

48.3 

70.8 

Calm     . 

o 

Clear     .     .      . 

0 

9 

30.02 

54-7 

53.0 

87.0 

Calm     . 

o 

Clear 

0 

ii 

29.95 

65.2 

60.0 

102.5 

Calm     . 

0 

Haze  and  cirri. 

I 

12 

29.93 

67.3 

60.0 

103-5 

Calm     . 

0 

Haze  and  cirri. 

I 

13 

29.84 

69.7 

61.9 

III.O 

Calm 

o 

Haze  and  cirri. 

I 

M 

29.84 

t>8.5 

61.3 

IIO.  2 

Calm     . 

o 

Haze  and  cirri. 

I 

15 

29.83 

67.7 

61.5 

99-5 

Calm"   . 

0 

I  la/.e  and  cirri. 

I 

1  6 

29.82 

68.2 

61.3 

96.0 

Calm     . 

o 

Haze  and  cirri. 

I 

17 

29.83 

70.2 

58.5 

71.0 

Calm 

o 

Haze  and  cirri. 

2 

Maximum,  73°.o.                       Minimum,  49°.o. 

Dec.  18,     10 

29.83 

66.7 

57-5 

112.5 

Calm     . 

o       Cirro-stratus   . 

2 

ii 

29.79 

71.2 

58.0 

I2O.O 

NW.      . 

2       Cirro-stratus   . 

3 

12 

29.78 

69.2 

57.0 

125.0 

NW.      . 

2       Cirro-stratus   . 

4 

13 

29.77 

68.5 

57-7 

95.8     NW.      . 

I        Cirro-stratus    . 

5 

»4 

29.76 

67.7 

57-2 

82.8     NW.      . 

I 

Cirro-stratus   . 

8 

15 

29.76 

66.2 

57-5 

94.5      NW.      . 

I 

Cirro-stratus    . 

8 

16 

29.82 

64.2 

54-5 

89.0 

NW.      . 

I 

Cirro-stratus   . 

7 

17 

29.83 

62.5 

51.8 

64.0 

NW.      . 

I 

Cirro-stratus   . 

5 

Maximum,  72°.g.                        Minimum,  4i°.o. 

Dec.  19,       8 

29.97 

44-7      41-5 

76.5      Calm     . 

.     0 

Clear     .      .     . 

o 

9 

29.96 

50.2 

46.3 

87.5 

Calm     . 

o 

Clear     .      .     . 

o 

10 

29.94 

55-7 

49-0 

IO2.O 

Calm     . 

0 

Clear     .      .      . 

0 

ii 

29.91 

59-4 

51.8 

IOI.O 

Calm     . 

o 

Clear     .      .      . 

o 

12 

29.89 

60.7 

52.9 

107.5 

S.      .      . 

I 

Clear     .     .      . 

0 

13 

29.89 

60.2 

52.5 

103.0 

S.      .      . 

I 

Clear     .      .      . 

o 

14 

29.89 

61.2 

53-0 

IO2.O 

S. 

I 

Clear     .      .      . 

0 

15. 

29.89 

59-5 

51.0 

103.5 

S.      .      . 

I 

Clear 

0 

1  6 

29.88 

58.2 

50.8 

104.0 

Calm     . 

0 

Clear     .      .      . 

o 

17 

29.87 

57.2 

51.0 

94-5 

Calm     . 

o 

Clear     .      .      . 

o 

18 

29.89 

52.2 

47-5 

55-5 

Calm     . 

0 

Clear     .      .      . 

0 

19 

29.90 

51-2 

47-o 

47-5 

S.     .     . 

I 

Clear     .      .      . 

o 

20 

29.92 

48.7 

46.0 

48.0  !  Calm     . 

o 

Clear     .      .     . 

o 

Maximum,  (>2°.2.                       Minimum,  44°.o. 

REPORT  OF  PROFESSOR  EASTMAN. 


125 


Date. 

Barometer. 

Thermometers. 

Wind. 

Weather. 

Dry. 

Wet. 

Solar. 

Direction. 

Force. 

Clouds. 

Portion 
cloudy. 

1870.         h. 

in. 

o 

0 

0 

Dec.  20,       8 

29.85 

56.2 

51-5 

53-6 

W.    .      . 

I 

Cumulo-stratus 

9 

9 

29.84 

57.  S 

53-0 

65.0 

w.  .    . 

2 

Cumulo-stratus 

9 

10 

29.83 

60.2 

54-0 

100.5 

W.    .      . 

2 

Cumulo-stratus 

6 

it 

29.79 

61.0 

54-0 

105.0 

W.     .        .    '         2 

Cumulo-stratus 

3 

12 

29.77 

61.7 

55.0 

112.  0 

W.    .      .          4 

Cumulo-stratus 

2 

13 

29.76 

62.2 

56.5 

III.O 

W.  SW  .          3 

Clear 

O 

14 

29.74 

62.2 

54-5 

105.0 

SW.        .          3 

Clear     .      .      . 

O 

15 

29-74 

61.2 

54-3 

102.5 

SW.        .          3        Clear     .      .      . 

0 

16 

29-75 

59.2 

53-0 

95.5 

SW.       .          3       Clear     .      .      . 

O 

17 

29.76 

57-2 

51-5 

67.0 

SW.       .          3 

Clear     .      .      . 

0 

Maximum, 

&3°.3.                       Minimum,  49°.  5. 

Dec.  21,       7 

29.74 

53-2 

48.2 

47-8 

Calm     .          o        Cirro-stratus    . 

2 

8 

29.74 

56.2 

50.2 

85.5 

Calm     . 

o        Cirro-stratus    . 

I 

9 

29.71 

57-2 

52.2 

Sg.S 

Calm     . 

o        Cirro-stratus    . 

I 

10 

29.68 

62.2 

55-2 

105.0 

SW.       . 

i 

Cirrus   . 

I 

it 

29.65 

63.7 

57-2 

109.0 

Calm     . 

o        Cirrus    . 

I 

I  2 

29.  62 

fi.1     'Z 

n8  o 

1  13.  0 

SW. 

2        C.  K.     .      .      . 

2 

13 

29.60         65.7 

gw»w 

59.0 

*  j  '  j 
113.0 

SW.        . 

3 

C    K.     .      .      . 

2 

14 

29.57          65.7 

'58.5 

110.5 

SW. 

2 

C   K 

2 

T  H 

20  so 

fii   8 

<?Q  6 

108  .0 

SW 

2        C    K.      .      .      . 

3 

1  -> 

16 

*y  •  j  j          ~-/  •  ~ 
29.61       ,  61.7 

jy  •  " 

ss.o 

83.0     SW.       . 

I 

C    K 

5 

Maxim  u  in 

66°.  8.                         Minimum,  47°.  o. 

On  the  2ist  there  were  unmistakable  signs  of  the  coming  change  in  the  weather.  The  barometer  was 
unsteady,  but  gradually  falling ;  the  low  bank  of  clouds,  of  a  peculiar  ashy  hue,  that  hung  over  the  Malta 
Channel,  threatened  wind  from  the  S.  W.  or  W.,  and  during  the  entire  day  Etna  was  wrapped  in  a  heavy 
mass  of  cumulus  clouds.  At  i1'  a.  m.  on  the  22d,  a  very  light  shower  came  on,  with  a  slight  sprinkle  of 
snow,  accompanied  with  lightning  and  thunder.  At  y1'  a.  m.  the  clouds  were  quite  dense  near  the 
horizon,  but  were  clearing  away  near  the  zenith.  The  clouds  seemed  to  condense  near  the  horizon,  and 
by  9h  30'"  a.  m.  only  light  flitting  clouds  were  to  be  seen  at  the  altitude  of  the  sun.  During  the 
morning  Etna  was  visible  for  about  three  hours,  and  it  was  evident  that  since  the  previous  morning  it 
had  experienced  a  heavy  fall  of  snow.  The  barometer  was  quite  low  during  the  morning,  and  in  fact 
all  day,  and  while  Etna  was  visible  in  the  morning  there  was  an  unusually  large  cloud  of  smoke  or  vapor 
(lowing  from  the  crater. 

At  1 11'  a.  m.,  I  attempted  to  make  a  sketch  of  the  spots  on  the  sun,  but  the  strong  wind  jarred  my 
telescope  so  much  that  I  was  obliged  to  give  up  the  idea. 

In  order  to  obtain  the  most  and  the  best  work  in  the  shortest  time,  I  arranged  the  following  plan,  which, 
so  far  as  circumstances  would  permit,  I  was  able  to  carry  out  in  every  respect : 

i".  Observe  first  contact. 

2°.  Observe  with  the  actinometer  until  five  minutes  before  the  beginning  of  totality,  occasionally  exam- 
ining the  edge  of  the  advancing  moon. 

3°.  Observe  the  time  of  the  beginning  of  the  total  phase. 

4°.  With  the  polariscope  observe — 1°.  The  dark  surface  of  the  moon;  2°,  the  sky  near  the  corona;  3°, 
the  corona,  especially  the  denser  portions. 


126  OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 

5°.  Observe  the  time  of  the  end  of  totality. 

6°.  Observe  with  the  actinometer  as  before. 

7°.  Observe  the  time  of  last  contact. 

Mrs.  Eastman  was,  as  in  1869,  to  make  the  usual  meteorological  observations,  and  observe  with  the  pho- 
tometer at  intervals  of  ten  minutes  during  the  progress  of  the  eclipse,  and  during  the  total  phase  to  make 
one  observation,  if  possible,  with  the  photometer,  and  read  the  solar  thermometer  once. 

By  noon  the  wind  had  considerably  increased  and  the  flying  clouds  were  increasing  in  density. 

At  the  time  of  first  contact,  though  the  sky  was  perfectly  clear  about  the  sun,  the  wind  disturbed  the 
telescope  so  much  that  I  could  not  get  a  good  image  of  the  sun's  limb  at  the  point  of  contact,  and  the  time 
of  contact,  as  I  observed  it,  n1'  39'"  12",  by  chronometer  Negus  1340,  which  I  used  for  all  time  observa- 
tions on  the  22d,  must  have  been  several  seconds  too  late. 

Soon  after  first  contact  I  attempted  to  make  some  observations  with  the  actinometer,  but  the  increasing 
and  quickly  moving  clouds  prevented  my  getting  more  than  two  good  readings,  and  though  I  made  several 
subsequent  trials  at  every  favorable  opportunity  during  the  day,  I  did  not  succeed  in  getting  a  single  com- 
plete set  of  observations. 

After  the  first  contact  the  cloudiness  increased  quite  rapidly,  and  about  twenty  minutes  before  the  total- 
ity a  dense  white  cloud  completely  obscured  the  sun,  its  increasing  proportions  threatening  to  frustrate  all 
our  hopes  for  success.  This  cloud  did  not  disappear  by  moving  away  in  a  mass,  but  seemed  to  melt  away 
from  a  point  in  the  vicinity  of  the  sun,  remains  of  it  completely  surrounding  the  sun  until  some  minutes  after- 
totality.  About  four  minutes  before  the  total  phase  a  rift,  about  three  times  the  diameter  of  the  sun,  appeared 
in  this  cloud,  through  which  the  outline  of  the  sun  could  be  easily  traced,  and  the  light  cirrus-like  clouds  that 
were  constantly  passing  over  this  space  were  dense  enough  to  enable  me  to  examine  the  decreasing  cusps  of 
the  sun  without  the  aid  of  the  colored  shade  for  the  eye-piece. 

As  the  crescent  of  light  gradually  decreased  the  boundary  of  the  aperture  in  the  cloud  grew  somewhat 
larger  and  more  distinct,  with  the  sun  apparently  in  the  center  of  this  cloud-frame,  and  the  light,  fleeting 
clouds  that  drifted  across  the  face  of  the  moon  became  less  dense  and  moved  with  a  lower  velocity.  After 
the  obscuration  of  the  sun  by  this  cloud  the  wind  increased  considerably  and  blew  in  fitful  gusts,  while  the 
chilly  sensation,  as  of  going  into  a  deep  cavern,  came  on  suddenly  and  to  such  an  extent  that  the  addition 
of  more  clothing  failed  to  counteract  its  effect.  The  phenomenon  of  total  obscuration  of  the  solar  light  was, 
of  course,  owing  to  the  apparent  difference  of  the  relative  diameters  of  the  sun  and  moon,  quite  different 
from  that  in  1869. 

In  1869  the  thin  crescent  faded  away  very  rapidly  from  the  cusps  toward  the  central  line,  while  at  the 
center  there  was  an  appreciable  breadth  of  light ;  but  at  Syracuse  the  crescent  of  the  same  breadth  was  at 
least  twice  the  angular  length  of  that  of  1869-,  and  broke  up  into  four  pieces,  all  of  them  seeming  to  disap- 
pear at  the  same  instant.  Just  previous  to  the  totality  I  attached  the  polariscope  by  means  of  the  adapter 
to  the  telescope  and  carefully  adjusted,  the  focus.  The  eye-piece  connected  with  the  polariscope  had  a 
magnifying  power  of  32,  and  with  this  eye-piece  I  observed  the  beginning  and  end  of  totality. 

I  noted  the  time  of  beginning  of  totality  at  i'1  3'"  5is.o  by  chronometer  1340.  I  immediately  turned 
the  telescope  upon  the  dark  face  of  the  moon,  and  saw  alternate  dark  and  light  bands  of  nearly  equal  inten- 
sity over  the  whole  surface,  but  the  distinction  was  a  little  less  marked  at  the  center  of  the  moon.  These 
bands  were  not  changed  in  distinctness  or  tint  during  a  complete  revolution  of  the  polariscope.  I  then 
moved  the  telescope  so  as  to  take  successively  into  the  field  portions  of  a  belt  of  the  sky  outside  the 
visible  limits  of  the  corona,  extending  completely  around  the  moon,  but  the  alternate  dark  and  light  bands 
remained  the  same  in  tint,  but  varied  in  intensity  or  distinctness,  according  to  the  position  of  the  clouds. 
Where  the  sky  was  nearly  clear  of  clouds  the  definition  of  the  bands  was  about  the  same  as  on  the  dark 
surface  of  the  moon,  but  the  definition  was  very  much  improved  whenever  a  denser  portion  of  the  cloud 
was  in  the  field.  I  then  moved  the  telescope  around  the  moon  in  such  a  way  as  to  keep  the  lower  and  . 
denser  portion  of  the  corona  near  the  middle  of  the  field,  with  results  similar  to  those  derived  from  the 
examination  of  the  sky  beyond  the  corona,  except  that  the  intensity  of  the  tint  of  the  bands  was  at  its  maxi- 
mum when  they  were  parallel  or  perpendicular  to  a  tangent  to  the  moon's  limb.  Once  I  thought  I  detected 
a  faint  tinge  of  green  in  the  bands,  but  I  was  not  able  to  see  it  again.  I  also  saw  a  faint  but  decided  red 
tinge  in  the  bands  over  what  I  at  first  took  to  be  a  very  dense  portion  of  the  corona,  on  the  southwest  limb  of 
the  sun,  but  on  more  careful  scrutiny  it  proved  to  be  a  cloud  moving  easterly.  I  then  turned  the  telescope  for 
an  instant  to  the  bright  edge  of  a  cloud  near  the  westerly  limb  of  the  sun,  and  there  saw  distinct  traces  of 


REPORT  OF  PROFESSOR  EASTMAN.  127' 

• 

color  in  the  bands,  though  the  tints  were  very  faint.  As  it  was  now  nearly  time  for  the  end  of  totality, 
I  brought  that  portion  of  the  moon's  limb  where  the  light  of  the  sun  would  re-appear  into  the  center  of  the 
field,  and,  during  the  few  remaining  seconds,  carefully  studied  the  appearance  of  the  corona  and  the  most 
conspicuous  protuberance. 

The  structure  of  the  corona  appeared  essentially  the  same  as  in  1869,  and  consisted  ot  three  distinct 
portions. 

That  portion  next  the  edge  of  the  moon,  in  many  cases  nearly  obscured  by  the  low  and  quite  continu- 
ous range  of  protuberances  which  stretched  along  the  limb  of  the  sun  for  about  150°,  was  nearly  white  and 
resembled  the  denser  portions  of  nebulae.  It  seemed  to  be  concentric  with  the  sun,  and  I  estimated  its 
height,  at  the  point  near  the  large  protuberance,  at  about  one  minute.  The  height  of  the  next  portion  above 
the  limb  of  the  moon  was  about  six  minutes,  and  it  had  a  decided  radial  structure,  especially  near  the  outer 
limit.  Its  color  was  silvery  white.  This  portion  seemed  to  be  concentric  with  the  sun,  and  its  form  was 
quite  symmetrical,  showing  no  change  whatever  in  its  outline  in  the  vicinity  of  the  protuberances. 

The  third  and  outer  portion  of  the  corona,  on  the  western  limb  of  the  sun,  consisted  of  three  projec- 
tions of  light  striated,  or  of  a  radial  structure,  resembling  the  short  bands  of  streamers  that  are  frequently 
seen  rising  from  the  auroral  arch.  One  of  these  projections  on  the  northwest  liriib  of  the  sun  was  quite 
small,  extending  not  more  than  five  minutes  above  the  limit  of  the  second  portion  of  the  corona.  The 
others,  one  on  the  southwest  and  one  on  the  northwest  limb  of  the  sun,  attained  an  altitude  of  about  nine 
minutes  above  the  second  division  of  the  corona. 

The  projections  from  the  main  portion  of  the  corona  were  a  silvery  or  grayish-white  color,  and  the  light 
was  steady  without  any  flickering.  • 

Near  the  extremities  of  these  projections  they  resembled  very  much  the  appearance  ot  the  sunlight  as' 
it  passes  through  the  interstices  of  the  clouds  near  sunrise  or  sunset.  The  only  protuberance  which  I  noted 
carefully  enough  to  enable  me  to  sketch  its  position  and  outline,  was  located  a  little  to  the  north  of  the  point 
where  the  sun's  light  re-appeared.  In  form  it  resembled  a  mushroom,  or  the  conventional  representation  of 
a  waterspout,  its  outer  limit  being  about  two  minutes  above  the  limb  of  the  moon.  Its  northern  limit  was 
quite  smooth  and  regular,  while  the  southern  edge  was  rough  and  jagged,  looking  as  if  a  strong  current  of 
wind  was  sweeping  the  lighter  portions  of  its  mass  to  the  southward,  and  showing  these  rough  edges  and 
floating,  irregular  filaments  in  projection.  The  color  of  the  southern  end  of  this  protuberance  was  a  lighter 
pink  than  the  main  portion  of  the  mass,  or  than  the  low  range  of  protuberances,  which  I  had  no  time  to 
examine  further  than  to  note  their  color  and  general  outline. 

The  end  of  totality  was  preceded  by  an  increasing  glow  near  the  limb  of  the  moon,  south  of  the  large 
protuberance,  and  announced  by  the  bursting  forth  of  a  mass  ot  light,  shaped  like  the  apex  of  a  sugar-loaf, 
which  spread  north  and  south  along  the  edge  of  the  moon  like  a  flash  of  lightning.  This  phenomenon  I 
noted  at  i1'  5'"  32S.5.  At  the  end  of  totality  I  immediately  finished  my  sketch  of  the  corona  and  protub,er- 
ances,  and  completed  my  fragmentary  notes  of  the  phenomena. 

About  fifteen  seconds  before  the  end  of  totality,  the  murmurs  and  exclamations  ot  the  people  who  had 
crowded  into  the  open  space  between  our  guards  and  the  prison,  became  so  loud  that  I  could  not  hear  the 
beat  of  my  chronometer,  and  Mrs.  Eastman  abandoned  her  general  observations  to  count  the  second  beats 
of  the  chronometer  aloud. 

During  totality  I  felt  some  hard  substance  strike  my  tace  several  times,  and  Mrs.  Eastman  noticed  the 
fall  of  a  few  small  hail-stones  at  that  time.  At  about  fifteen  seconds  before  the  end  of  totality  the  clouds 
and  haze  had  nearly  disappeared  about  the  sun,  and  in  five  minutes  afterward  it  was  perfectly  clear.  Mrs. 
Eastman  succeeded  with  all  her  contemplated  observations  except  with  the  photometer,  and  only  by  her 
assistance  was  I  enabled  to  observe  the  time  of  the  end  of  totality. 

Before  totality  the  flying  clouds  so  interfered  with  every  set  of  observations  with  the  photometer  that 
their  value  was  entirely  destroyed,  and  during  totality  the  whole  aperture  of  the  instrument  did  not  admit 
light  enough  to  illuminate  the  image  at  the  base  of  the  tube.  After  totality,  the  flying  clouds,  though 
they  obscured  the  sun  but  a  few  minutes  at  a  time,  destroyed  the  value  of  the  observations  for  the  purposes 
of  comparison,  and  they  have  therefore  been  entirely  omitted. 

The  clouds  gradually  decreased,  and  about  the  time  of  last  contact  had  entirely  disappeared  in  the  vicinity 
of  the  sun,  while  the  wind  had  nearly  died  away.  I  observed  the  last  contact  with  great  care  and  very 
accurately,  I  think,  at  21'  22"'  53s-5. 


'128 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22,  1870. 


The  meteorological  observations  during  the  day,  as  made  by  Mrs.  Eastman,  are  shown  in  the  following 
table,  where  all  the  scale  readings  have  been  corrected  when  necessary,  and  the  barometer  readings  have 
been  corrected  for  temperature. 


Date. 

Barometer. 

Thermometers. 

Wind. 

Weather. 

Dry. 

Wet. 

Solar. 

Direction. 

Force. 

Clouds. 

Portion 
cloudy. 

1870.        h.  m. 

in. 

o 

0 

0 

Dec.  22,      8-    o 

29.36 

52.4 

49-5 

86.5 

W.    .      . 

i 

C.  K.           2 

9    o 

29.36 

54.9 

50.2 

90.0 

W.    .      . 

i 

C.  K.           i 

10      0 

29.36 

57.3 

52.0 

101.5 

W.    .      . 

i 

C.  K. 

0.5 

II       0 

29.36 

58.7 

49-5 

107.5 

W.    .      . 

i 

C.  K. 

i 

12      0 

29-35 

59-7 

51-5 

116.5 

W.    .      . 

i 

C.  K. 

i 

12    30 

29.35 

59-6 

51-2 

115.2 

W.    .      . 

i 

C.  K. 

2 

12   40 

29-35 

57.6 

49.8 

Til.  2 

W.    .      . 

i 

C.  K. 

2 

12    50 

29-35 

58.9 

51.0 

102.5 

W.    .      . 

2 

C.  K. 

2 

13     o 

29.35 

58.6 

51.0 

102.5 

W.   .      . 

2 

C.  K. 

3 

13  10 

29-35 

57-5 

50-5 

99-5 

W.    .     . 

2 

C.  K. 

3 

13   20 

29.35 

56.7 

50.2 

77-5 

W.    .      . 

2 

C.  K.           3 

13    30 

29.36 

55-4 

49-2 

65-5 

W.   .      . 

3 

C.  K.            4 

13   40 

29.36 

54-7 

48.8 

65.1 

W.    .      . 

2 

C.  K.           3 

13    50 

29.37 

54-2 

48.6 

57-0 

W.byN. 

3 

C.  K. 

4 

14    o 

29.38 

54-0 

48.2 

53-5 

W.    .      . 

2 

C.  K. 

4 

M     5 

29.38 

53-7 

48.0 

53-0 

W.    .      . 

3 

C.  K. 

4 

14    20 

29.38 

53-2 

48.0 

60.6 

W.    .      . 

3 

C.  K.           3 

M  3° 

29.38 

53-2 

48.0 

67.5 

W.    .      . 

2 

C.K.          3 

14  40 

29.38 

53-2 

48.0 

78.5 

W.    .      . 

2 

C.  K.           3 

M  50 

29.38 

53-2 

48.1         77.4 

W.    .      . 

2 

C.  K.          2 

15     o 

29-39 

53-7 

48.6 

85.8 

W.    .      . 

I 

C.  K. 

2 

15  10 

29-39 

53-4 

47.8 

74.0 

W.    .      . 

I 

C.  K. 

2 

15    20 

29-39 

53-7 

48.0 

77-5 

Calm     . 

0 

C.  K. 

I 

15    30 

29-39 

54'-  4 

48.1 

82.7 

W.byN. 

I 

C.  S. 

I 

Maximum  temperature  from  December  21  I7h  to  December  22  i6h       .       .       .     6i°.s 
Minimum  temperature  from  December  21  i7h  to  December  22  i6h        .       .       .      52°. o 

Amount  of  rain  and  snow  on  the  morning  of  the  22d  o  .02  inch. 

Fig.  i  represents  the  mean  curves  of  the  dry  and  wet  thermometers  for  six  days  and  the  observations 
on  the  22d. 

Fig.  2  represents  the  mean  curve  of  the  solar  thermometer  for  six  days  and  the  observations  on  the  22d. 
On  the  morning  of  the  22d,  my  chronometer  No.  1340  was  compared  with  No.  1115,  used  by  Profes- 
sor Harkness,  and  I  also  compared  them  after  the  observation  of  the  last  contact.     The  following  are  the 
results : 

No.  1340.  No.  1115. 

h.      m.         s.  h.      m.      s. 

9       5     39-2  920 

2     32     39.8  2     29     o 


REPORT  OF  PROFESSOR  EASTMAN. 
Fig.  i. 


I  29 


7°° 


65 


YS* 


40" 


12" 


12" 


M>an  Curve  for  6  Hays 


Dry  Tliermometer 


Jbservatiaiis  on  tfieZ 


MeaiiCarvcJbr&Dcys 


Wet  Thermometer 


T/|h, 


I5lv 


16' 


7°° 


65° 


-6')' 


-55° 


-  5°° 
-60" 


55° 


50° 


45° 


I6K 


Prof.  JKEastmai  i  V.  SK  del . 
17— K 


130 


OBSERVATIONS  OF   THE  ECLIPSE  OF  DECEMBER  22,  1870. 

Fifi.  2. 


i-rol.  J.B  Eastnum  V.  S.N.  del. . 


REPORT  OF  PROFESSOR  EASTMAN. 


From  Professor  Harkness's  observations,  No.  1115  was  found  to  be  ib  2'"  458-7  slow  of  local  mean  time 
at  both  the  morning  and  afternoon  comparisons;  hence  the  errors  of  No.  1340  when  the  comparisons  were 
made  were  — oh  59'"  68.5  and  — ou  59™  53.9,  with  a  gaining  rate  of  os.n  an  hour.  Applying  the  corrections 
deduced  from  the  above  data  to  the  observed  times  of  contact,  and  comparing  the  results  with  the  times 
computed  by  Professor  Hall  from  the  data  in  the  American  Nautical  Almanac,  assuming  the  latitude  of 
Syracuse  to  be  +  37°  3'  53"  and  the  longitude  — 61'  9™  258.6  from  Washington,  we  have  the  following  table  : 


Prof.  Hall's 

Computed  Time. 

Observed  Time. 

C.-O. 

** 

h.     m.       s. 

h.     m.      s. 

s. 

First  contact      .... 

o    38     15.8 

o     38     18.2 

2.4 

Beginning  of  totality   . 

2      3       1.8 

2      2     57.1 

+     4-7 

End  of  totality  .... 

2       4     43.0 

2       4     38.6 

+     4-4 

Last  contact       .... 

3      22         5.1 

3     21     59-4 

+     5-7 

The  accompanying  sketch  was  made  from  the  appearance  of  the  phenomena  in  the  telescope  when  the 
principal  prominence  was  near  the  center  of  the  field,  just  before  the  end  of  totality,  and  to  avoid  any  chance 
for  confusion  the  sketch  has  been  finished  in  the  inverted  position  in  which  it  was  seen  in  the  telescope. 

On  the  night  of  the  i2th  December  I  saw  a  few  meteors,  and  the  observations  are  given  in  Addendum  A. 
While  in  Malta  I  was  greatly  indebted  to  Mr.  Lyell  T.  Adams,  the  American  Consul,  who  spared  no 
pains  to  make  our  forced  stay  an  agreeable  one;  to  Captain  G.  L.  Tupman,  of  the  English  Navy,  and  Mr. 
Rosenbusch  for  many  courtesies ;  and  to  Rear-Admiral  Hastings  R.  Yelverton,  commanding  the  English  fleet 
in  the  Mediterranean,  who  very  kindly  offered  to  carry  us  to  Syracuse  in  his  dispatch-boat  if  the  regular 
steamer  did  not  go  in  season. 

At  Syracuse  the  American  Consular  Agent,  Signer  Nunzio  Stella,  was  very  assiduous  in  his  courteous 
attentions  to  our  party  and  rendered  us  all  the  aid  we  could  desire,  as  did  also  Mr.  Frederick  Behn,  the 
American  Consul  at  Messina.  I  am  also  under  obligations  to  the  Prefect  and  the  Syndic  of  Syracuse,  to 
Colonel  Rossi,  Commandant  of  the  King's  troops  in  Syracuse,  to  Signor  Bisani,  the  English  Consul  in  the  city, 
and  to  the  Syndic  of  Augusta;  in  fact,  this  list  might  be  extended  to  contain  the  names  of  all  the  government 
officials  and  scientific  men  whom  I  met  in  England  or  on  the  continent,  since  all  manifested  a  strong  desire 
to  aid  us  officially  and  socially  whenever  an  opportunity  occurred. 

As  soon  as  the  storm  which  came  on  after  the  eclipse  had  subsided,  I  left  Sicily  for  the  continent  and 
reached  Washington  on  the  iSth  February,  1871. 
Very  respectfully,  your  obedient  servant, 

J.  R.  EASTMAN, 
Professor  of  Mathematics,  U.    S.  Navy. 
Commodore  B.  F.  SANDS,  U.  S.  N., 

Superintendent  U.  S.  Naval  Observatory,  Washington,  D.  C. 


132 


OBSERVATIONS  OF  THE  ECLIPSE  OF  DECEMBER  22    1870. 


ADDENDUM     A. 
Meteors  observed  at  Syracuse,  Sicily,  December  12,  1870. 

The  observations  were  made  from  the  tower  of  the  "  Albergo  della  Vittoria,"  and  the  tracks  were 
recorded  on  a  temporary  chart  hastily  constructed  for  the  occasion. 

Only  the  southern  portion  of  the  heavens  was  mapped  on  this  chart,  as  I  intended  to  observe  to  the 
southward  and  note  only  such  stars  as  might  be  seen  by  Captain  G:  L.  Tupman  at  Valetta,  Malta. 

The  time  was  taken  from  a  pocket-watch,  which,  by  comparison  with  our  chronometers,  was  found  to  be 
fifty-five  seconds  slow  of  Syracuse  mean  time. 

The  times  given  in  the  following  table  have  been  reduced  to  Syracuse  mean  time. 

Besides  the  meteors  whose  paths  are  given  I  saw  thirteen  that  appeared  in  the  east  and  the  west,  but 
beyond  the  limits  of  the  chart. 


Number. 

Magnitude. 

Time  of 
Appearance. 

Path. 

Beginning. 

End.  . 

h.    m.     s. 

h.    m. 

0                    / 

h.    m. 

0                 1 

I 

3 

8     42     25 

3     io 

-17      o 

2     36 

-  23   30 

2 

4 

45     10 

2      32 

+     4     30 

I     52 

—    I    15 

3 

3 

8     59     55 

3     32 

+    22      30 

3       I 

+  17   30 

4 

3 

9       2     10 

2      42 

+    21      30 

2       9 

+   17      o 

5 

2 

2      25 

2      41 

+    20        0 

I     47+12     30 

6 

4 

io    35 

3     43 

—     12         0 

3     18    —   16     30 

7 

3 

21       30 

4     37 

—    12        O 

4     io   —  :6      o 

8 

4 

22      25 

3     26 

+      7      30 

3     22    +     6      o 

9 

4 

26      o 

3       7 

+       I      30 

2     28    —     6      o 

10 

3 

35     45 

4       o 

-     5     30 

3     32    —   io       o 

ii 

3 

42    40 

4       2 

+      20 

3     35    -     2      o 

12 

2 

48     io 

2       IO 

+   io    30 

I     33    +     5       o 

13 

3 

9     51     io 

2         7 

+   13     3° 

i     36 

+       90 

The  light  from  all  these  meteors  was  white,  but  none  of  them  left  trains. 

Most  of  them  moved  rapidly,  but  as  I  was  observing  alone  I  did  not  attempt  to  note  the  duration  of 
each  flight. 

J.  R.  EASTMAN, 
Professor  of  Mathematics,  U.  S.  Navy. 


Plak-  I 


'lie  Total  Solar  Kdipso  of  December  22,  1870,  as  seen 
al  Syracuse,  with  a  I'?,  inch   telescope-by 

Captain    (;.  I,  Tupnian,  H    M.  A 


Plate  II. 


IVol MR. Kaufman.  I'.S.N  Atl 


Sketch  of  the  Corona  and  Protuberances  on  the  western  limb  of  the  Sun, 

near  the.  end  of  the  total  phase'of  the  eclipse  of  Dec  22, 1870  by 

Prof.  J.R.  Eastman.  U.S.N. 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


